Two months ago, J.D. Vance had this thing locked up.

The VP was sitting at 56% on Kalshi's "2028 Republican nominee for President" market. Rubio was stuck in the low teens. DeSantis was an afterthought. The general vibe was: "Vance is Trump's guy. This is settled."

It is not settled.

As of today, here's where the Kalshi market stands:

That's a 19-point swing in Vance's odds and a near-tripling of Rubio's. The total volume on this market? Over $21.8M.

Polymarket tells a similar story. Vance at 38%, Rubio at 27%. The gap was 40+ points in November. Now it's single digits.

So what happened?

Three words: the Iran war.

The U.S. started striking Iran on February 28. And while Vance was busy being what Trump called "philosophically a little bit different" and "maybe less enthusiastic about going," Rubio was front and center.

NBC News reported that right after the strikes started, Trump polled a room full of GOP donors at Mar-a-Lago about who they'd want as the 2028 nominee.

The room picked Rubio.

Trump has since called Rubio the best Secretary of State "in the country's history."

Vance, meanwhile, ran in 2024 as a hardline anti-interventionist. Now he's stuck defending a war he probably wouldn't have started. That's not a great look for a primary.

Here's where it gets interesting for prediction market traders.

The polls and the prediction markets are telling two very different stories right now.

The polls still love Vance. A J.L. Partners poll from late February had Vance at 53% and Rubio at 14% among likely GOP primary voters. Emerson College Polling puts it at 59% to 19%.

Spencer Kimball, executive director of Emerson College Polling, said Republican voters are strongly behind Vance, with independents who plan to vote in the Republican primary also favoring him, though by a narrower margin.

But the prediction markets? They're pricing in something the polls haven't caught up to yet.

Kalshi and Polymarket traders are betting that the Iran war changes the calculus. That Trump's public praise for Rubio matters more than early voter surveys taken before bombs started falling. That Vance's anti-interventionist brand is a liability when the administration he's part of is running an air campaign.

I'll say this: prediction markets tend to move before polls do. In 2024, Polymarket had Trump's odds climbing weeks before the polling averages shifted.

So the question becomes: is the prediction market ahead of the curve again? Or is it overreacting to a news cycle that'll fade?

Here's my read:

The Iran war is a double-edged sword for Rubio. Right now, it's giving him all the attention and all the praise from Trump. But the conflict already has a low approval rating. If it drags on for months (and looking at the Strait of Hormuz situation, it might), public fatigue could drag Rubio down with it.

Vance's problem is different. D. Stephen Voss, a political science professor at the University of Kentucky, put it well: Vance's real challenge isn't MAGA. He has that base. His problem is motivating the voters who usually stay home but show up for Trump himself. Vance just doesn't have Trump's hold on people.

Neither Rubio nor Vance has officially announced a run. Trump hasn't endorsed either of them. He said in an NBC interview: "JD is fantastic, and Marco is fantastic." Classic Trump -- keeping both horses in the race while he watches from the owner's box.

At 37 cents for Vance and 28 cents for Rubio on Kalshi, here's how I'd frame the bet:

If you think the Iran war fades and Vance's incumbency advantage holds, 37 cents for a dollar looks like a steal.

If you think Rubio keeps riding the war hero wave and Trump keeps praising him in public, 28 cents could be the bargain.

Either way, I wouldn't touch anyone outside the top two at these prices. DeSantis at 5 cents? Trump Jr. at 4 cents? Tucker Carlson at 4 cents?

That's donation money, not investment money.

The real trade here is the spread between Vance and Rubio. Nine points. And shrinking.

Watch the Iran war. Watch Trump's mouth. That's all that matters for this market right now.

Oof! Vance's odds have dropped nearly 20 points since January on Kalshi's 2028 Republican nominee market.

Wild stat: Polymarket's 2028 Republican nominee market has done over $407M in total volume. This thing is a beast.

Trump told NBC he won't endorse either Vance or Rubio yet -- "We have three years to go."

The Iran war is making Rubio look presidential. But public approval of the conflict is low and getting lower.

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