J.D. Vance is a coin flip to be the 2028 Republican nominee, and that makes him the clearest frontrunner in American politics. As of September 21, 2026, Polymarket prices the vice president at 51.2¢ and Kalshi at 45–46¢. The next candidate, Secretary of State Marco Rubio, trades at 15.6¢ on Polymarket and 20–21¢ on Kalshi. Nobody else is above 5¢.
Those 2028 Republican nominee odds tell a simple story with a complicated wrinkle. The simple story is that the party's succession runs through the vice president. The wrinkle is that the two biggest venues disagree about how likely that is, by almost six points on Vance and five on Rubio — enough that the gap is currently a live arbitrage.
This page covers the full field, the case for and against the two leaders, why Donald Trump still trades at 2¢, and exactly what the cross-venue trade looks like once fees and time are counted. Polymarket's version of the market has traded about $707 million and Kalshi's about 65 million contracts.
| Candidate | Current role | Polymarket | Kalshi (bid / ask) | Gap |
|---|---|---|---|---|
| J.D. Vance | Vice President | 51.2¢ | 45¢ / 46¢ | Polymarket +5.8 |
| Marco Rubio | Secretary of State | 15.6¢ | 20¢ / 21¢ | Kalshi +4.9 |
| Tucker Carlson | Media host | 3.2¢ | 2.5¢ / 2.6¢ | Polymarket +0.7 |
| Ron DeSantis | Governor of Florida | 2.9¢ | 4.3¢ / 4.4¢ | Kalshi +1.5 |
| Donald Trump | President | 2.1¢ | 2.1¢ / 2.3¢ | Even |
| Ted Cruz | US Senator, Texas | 1.8¢ | 1.7¢ / 1.8¢ | Even |
| Donald Trump Jr. | Businessman | 1.6¢ | 3.3¢ / 3.5¢ | Kalshi +1.9 |
| Ivanka Trump | Businesswoman | 0.9¢ | 1.4¢ / 1.5¢ | Kalshi +0.6 |
| Thomas Massie | US Representative, Kentucky | 0.7¢ | 1.1¢ / 1.2¢ | Kalshi +0.5 |
| Glenn Youngkin | Former Governor of Virginia | 0.4¢ | 0.8¢ / 1.0¢ | Kalshi +0.5 |
| Pete Hegseth | Defense Secretary | 0.4¢ | 0.6¢ / 0.9¢ | Kalshi +0.3 |
| Josh Hawley | US Senator, Missouri | 0.4¢ | 0.5¢ / 0.6¢ | Kalshi +0.2 |
Prices come from PredictReport's tracker on the morning of September 21, 2026. The live Republican nominee page refreshes every ten minutes. A contract pays $1 if that person is the nominee, so 51.2¢ reads as a 51.2% chance; our explainer on prediction market odds shows how to convert that to American odds.
J.D. Vance at 51%: The Clear Frontrunner
A 51% price two years before the primaries is extraordinarily high for a nomination market. For comparison, the Democratic leader in the parallel market trades at 18%. The market is saying that the Republican succession is largely settled and that the main risk is something unexpected rather than a rival.
Vance's price has been remarkably stable. Since September 1 it has moved between 50.7¢ and 52.6¢ on Polymarket, a range of under two points in a market that has traded hundreds of millions of dollars. Stability like that usually means large holders are comfortable where the price is, and new information has not arrived to move them.
The case for Vance is institutional. He holds the office that has historically produced nominees, he has the president's backing in a party where that endorsement has decided primaries for a decade, and no major rival has declared. The case against is time. Two years is long enough for a scandal, a falling-out, a health event, or a political shift that nobody is pricing today. At 51¢, the market is paying roughly even money that none of those happens.
What that means for a buyer: $100 at 51.2¢ buys about 195 contracts, which pay $195 if Vance is nominated — a $95 profit for tying up $100 until mid-2028. Whether that is attractive depends on your view, but it is also worth comparing against the roughly 4% a year Kalshi pays on idle cash, a point we return to below. Our Kalshi review covers the interest programme.
Marco Rubio and the Case for a Different Heir
Rubio is the only other candidate the market takes seriously, and the two venues disagree sharply on how seriously. Kalshi prices him at 20–21¢; Polymarket at 15.6¢. That is a gap of nearly a third in implied probability.
His Polymarket price has also been the most active in the field. It started September at 17.8¢, touched 20¢ on September 7, and has drifted down to 15.6¢. The Rubio case rests on his experience and standing within the administration, and on the possibility that the party chooses a different profile than the vice president. It also rests on a scenario the market treats as plausible: that Vance and Rubio end up on the same ticket in some order.
The pattern across the two leaders is consistent. Polymarket prices Vance higher and Rubio lower; Kalshi does the reverse. The two venues have different users — Polymarket settles in USDC and draws heavily from crypto traders, Kalshi settles in dollars and draws a broader US retail base — and the gap looks like two crowds with different views rather than random noise. Our Polymarket review covers who trades there.
Why Donald Trump Trades at 2¢
The sitting president trades at 2.1¢ on Polymarket and 2.1–2.3¢ on Kalshi. The 22nd Amendment bars anyone from being elected president more than twice, which is why the market treats a Trump nomination as a remote possibility rather than a real candidacy.
The contract is not zero because contracts are rarely zero on anything a large number of people discuss. A 2¢ price means someone is willing to pay two cents for a scenario they consider worth the lottery ticket, and someone else is willing to take their money. On contracts priced this low, the spread and fees are a large share of the price. Kalshi's fee formula — 0.07 × contracts × price × (1 − price) — is small in absolute terms at 2¢, but the bid–ask spread alone can be a tenth of the price. Our Kalshi fees explainer walks through the formula.
More generally, long-shot contracts across prediction markets tend to be overpriced, a pattern known as the favourite–longshot bias. That is not a reason never to buy a 2¢ contract, but it is a reason to be sceptical that the cheap side is the value side. Our expected value guide explains the arithmetic.
The Rest of the Republican Field
Below the top two, the market is a list of scenarios. Tucker Carlson at 3.2¢ and Ted Cruz at 1.8¢ represent the possibility of a contested primary against the vice president. Ron DeSantis, at 2.9¢ on Polymarket but 4.3–4.4¢ on Kalshi, ran in 2024 and left the race in January of that year; his term as governor of Florida ends in January 2027.
The family entries are where the venues disagree most in relative terms. Donald Trump Jr. trades at 1.6¢ on Polymarket and 3.3–3.5¢ on Kalshi, more than double. Our scanner currently flags that gap as a small arbitrage, returning about 0.7% after fees. Ivanka Trump shows the same direction at a smaller size.
Glenn Youngkin, Pete Hegseth and Josh Hawley sit below 1¢. At those prices, the markets are thin enough that a single order can move them, and the quoted prices are closer to suggestions than to tradeable levels. Our guide to prediction market liquidity explains how to tell a real price from a stale one.
How the Republican Odds Moved in September
| Candidate | Sept 1 | Sept 21 | Change | September range |
|---|---|---|---|---|
| J.D. Vance | 52.0¢ | 51.2¢ | −0.8 | 50.7¢ – 52.6¢ |
| Marco Rubio | 17.8¢ | 15.6¢ | −2.2 | 15.6¢ – 20.0¢ |
| Tucker Carlson | 2.6¢ | 3.2¢ | +0.6 | 2.6¢ – 3.2¢ |
| Ron DeSantis | 2.5¢ | 2.9¢ | +0.4 | 2.5¢ – 2.9¢ |
| Ted Cruz | 1.2¢ | 1.8¢ | +0.6 | 1.2¢ – 1.8¢ |
Polymarket prices from PredictReport's tracker. The month's only meaningful move was Rubio's: up to 20¢ in the first week, then a steady fade. Vance barely moved. The small gains for Carlson, DeSantis and Cruz came from Rubio's decline being redistributed rather than from anything specific to them. The live page shows where each stands today.
The Vance Arbitrage, Worked Through
This is the most discussed cross-venue trade in politics, so it is worth doing properly. The trade buys Vance YES on Kalshi, where he is cheaper, and Vance NO on Polymarket, where YES is dearer.
| Leg | Venue | Price paid |
|---|---|---|
| Buy Vance YES | Kalshi (ask) | 46.0¢ |
| Buy Vance NO | Polymarket (1 − 51.2¢ bid) | 48.8¢ |
| Combined cost before fees | 94.8¢ | |
| Payout, whoever is nominated | $1.00 |
If Vance is nominated, the Kalshi leg pays $1 and the Polymarket leg pays nothing. If he is not, the reverse. Either way the pair pays $1 for 94.8¢, a gross margin of 5.2¢. After Kalshi's fee and Polymarket's taker fee, which our scanner applies at the top of Polymarket's 0.75–1.80% range to avoid overstating the edge, the all-in cost is about 97.7¢ and the return about 2.4%.
Now the part most write-ups skip. The contracts resolve in the second half of 2028, so the money is locked for roughly two years. A 2.4% return over that period annualises to about 1.1%. Kalshi pays roughly 4% on idle cash; Polymarket pays nothing. So the arbitrage currently earns less than simply leaving the Kalshi half of the money uninvested. It is a real, risk-free-looking profit that loses to a savings rate.
There is also resolution risk. The trade only works if both venues settle on the same event in the same way. Nomination markets are relatively clean — a formal nomination is hard to dispute — but read both rulebooks before assuming the two NO and YES contracts are exact mirrors. The Rubio gap works the same way in the opposite direction, at about 2.1% after fees. Our arbitrage guide covers the execution, and the live scanner shows current returns and annualised yields for every gap it finds.
What Sitting Vice Presidents Tell You
The strongest argument for Vance's price is historical. Since 1960, every sitting vice president who actively sought his party's nomination has won it: Richard Nixon in 1960, Hubert Humphrey in 1968, George H.W. Bush in 1988 and Al Gore in 2000. The vice presidency concentrates donors, staff and party loyalty in a way no other office does.
The weaker part of that record is the general election: of those four, only Bush won the presidency. And the precedent assumes the vice president stays aligned with the president; Mike Pence ran for the 2024 nomination as a former vice president estranged from his former running mate and left the race before a vote was cast. For a nomination contract, though, the base rate points one way. If anything, 51% looks modest for a sitting vice president with the president's support — which is precisely the argument Polymarket's traders are making against Kalshi's. Our guide to prediction market accuracy covers how often long-dated favourites deliver.
How the Republican Nomination Market Resolves
The contract resolves on the person the Republican Party formally nominates for president at its 2028 convention. It does not resolve on primary wins, polling, or endorsements. If the presumptive nominee withdrew before the convention, the market would pay whoever the delegates chose instead — which is exactly what happened on the Democratic side in 2024.
Each venue publishes its rules, including the resolution source and what happens in edge cases such as a withdrawal after the convention. Read them before trading, especially if you hold opposite sides on the two venues. Our explainer on how prediction markets resolve covers what to look for.
How to Trade the 2028 Republican Nomination
Kalshi is the regulated default for US traders, settling in dollars and paying interest on idle cash. Polymarket has the deeper order book in this market and settles in USDC. Polymarket vs Kalshi compares the two in detail, and our ranking of the best prediction market apps covers the wider field. If the mechanics are new, start with how prediction markets work.
Buy on whichever venue is cheaper for the side you want: Vance is cheaper on Kalshi, Rubio on Polymarket. Use limit orders rather than crossing the spread — our guide to limit orders explains why that matters most on long-dated contracts. And if you hold a view on the party rather than the person, the 2028 party market is the cleaner instrument; our 2028 Democratic nominee odds cover the other side of the race.
Profits are taxable when realised, and Kalshi issues a 1099-MISC; see our prediction market tax guide. Political contracts are contested in several states, so check our legal guide before trading.
Frequently Asked Questions
Who is the favorite for the 2028 Republican nomination?
J.D. Vance, at 51.2¢ on Polymarket and 45–46¢ on Kalshi as of September 21, 2026. Marco Rubio is second at 15.6¢ on Polymarket and 20–21¢ on Kalshi, and no one else is above 5¢.
What are Marco Rubio's odds of winning the 2028 nomination?
About 16% on Polymarket and 20–21% on Kalshi. His Polymarket price touched 20¢ on September 7 before fading through the month.
Can Donald Trump run for president in 2028?
The 22nd Amendment bars anyone from being elected president more than twice. Prediction markets price a Trump nomination at about 2¢, which reflects that constraint.
Why is J.D. Vance cheaper on Kalshi than Polymarket?
The two venues have different users and separate order books, and their prices drift apart. Polymarket's traders price Vance higher and Rubio lower, while Kalshi's do the opposite. See Polymarket vs Kalshi.
Is there an arbitrage on the Republican nominee market?
Yes, on current prices. Buying Vance YES on Kalshi at 46¢ and Vance NO on Polymarket at 48.8¢ costs 94.8¢ for a guaranteed $1, about 2.4% after fees. Because the money is locked until 2028, that is only about 1.1% a year. Our arbitrage scanner tracks it live.
Has a sitting vice president ever lost the nomination?
Not since 1960 among those who actively sought it. Nixon, Humphrey, George H.W. Bush and Gore all won their party's nomination as sitting vice presidents.
When does the Republican nominee market pay out?
When the party formally nominates its candidate at the 2028 convention. Contracts do not settle on primaries or polls.
Should I buy Vance on Polymarket or Kalshi?
On whichever is cheaper at the time you buy. On September 21, 2026, Vance cost 46¢ on Kalshi against 51.3¢ on Polymarket — the same $1 payout for about 10% less money.
