2028 Presidential Election

The 2028 presidential cycle is the deepest durable political market on the board: $986k a day on Polymarket's general-election Categorical, $701k on Kalshi's Democratic nominee book, $472k on Polymarket's. Nothing settles for more than two years, which makes this the cleanest long-horizon price discovery available anywhere.

The Democratic nomination lead has changed hands. This workspace was built around Gavin Newsom as the front-runner. Alexandria Ocasio-Cortez now leads on both exchanges—19.1% to Newsom's 17.0% on Polymarket, 17% to 16% on Kalshi—with Jon Ossoff a close third at 15.4% and 14%. Three candidates inside five points on a book turning over $1.17M a day across two venues.

And AOC is not just the price leader—she is most of the book. Her nomination contract carries $151.9k of Polymarket's $471.9k and $149.1k of Kalshi's $700.7k: roughly a third and a fifth of all flow, and the deepest single leg in each. Newsom's Polymarket leg carries $9.6k against her $151.9k, a sixteen-to-one gap on a two-point price difference.

The general-election winner books. Polymarket has JD Vance at 23.1%, AOC at 12.7%, Marco Rubio at 12.4%, Ossoff at 9.5%, Newsom at 9.2%. Kalshi has Vance at 18% and Rubio at 16%—a five-point cross-exchange gap on Vance and a four-point gap on Rubio, in opposite directions.

That is a large disagreement for two books this deep, and it is entirely about the Republican side: the two exchanges price the Democratic field within a couple of points of each other. Polymarket sees Vance as the clear Republican; Kalshi sees a two-man race.

The two names that define the cycle, priced on both exchanges. Vance is the general-election favorite everywhere but the size of the lead depends on the venue: 23.1% Polymarket, 18% Kalshi. AOC is the Democratic nomination favorite on both books and the second-likeliest president on Polymarket at 12.7%, where her leg carries $108.1k—the deepest contract in a $986k book.

Note the internal consistency check: AOC prices at 19.1% for the nomination and 12.7% for the presidency on Polymarket, implying a 66% conditional general-election win. Vance prices at roughly 43% for the Republican nomination and 23.1% for the presidency, implying 54%. Both cannot be right in a two-party race.

The four nominee books, two exchanges each. The Democratic field is a genuine three-way: AOC 19.1 / Newsom 17.0 / Ossoff 15.4 on Polymarket, AOC 17 / Newsom 16 / Ossoff 14 on Kalshi. Kamala Harris sits fourth at 7.5-9.4%, Pete Buttigieg and Mark Kelly around 5%.

The Republican field is not a race. Vance prices at 43% on both books with Rubio at 23-24% and Ron DeSantis a distant third around 3-5%. Two candidates account for two-thirds of the Republican book against a Democratic book where the top three account for barely half.

Kalshi's matchup Categorical prices specific general-election pairings rather than individual candidates. Newsom vs Vance leads at 11%, Newsom vs Rubio at 9.5%, AOC vs Vance at 9%—and the AOC-Vance pairing carries $264 of the book's $841, by far the most flow in a very thin market.

The matchup book is the only place on any exchange where you can read the joint distribution rather than two marginals. It is thin enough that the prices are indicative at best, but its ordering—Newsom pairings ahead of AOC pairings—contradicts the nominee books, which now have AOC ahead.

• The Democratic lead flipped and the flow says it is not close. AOC ahead of Newsom by two points on both books, but with sixteen times Newsom's Polymarket volume and four times his Kalshi volume. When price is tight and flow is lopsided, the price usually follows the flow.
• The exchanges disagree about the Republicans, not the Democrats. Vance 23.1% Polymarket against 18% Kalshi; Rubio 12.4% against 16%. Five and four points respectively, on the two deepest political books on either venue. That is the most persistent cross-exchange gap in this workspace.
• The conditional probabilities do not reconcile. AOC's Polymarket pair implies she wins 66% of general elections she contests; Vance's implies 54%. In a two-party race those should sum toward 100% for the two most likely nominees, and they do not.
• The Republican book is a two-man race; the Democratic book is not a race yet. Vance and Rubio account for roughly two-thirds of the Republican field. The top three Democrats account for barely half.
• The matchup book contradicts the nominee books. Kalshi's joint-outcome market still ranks Newsom pairings ahead of AOC pairings. It carries $841 a day, so this is a staleness artifact rather than a signal—but it is the kind of stale corner that resolves violently.
• Two years of runway. Nothing here settles before November 2028. Expect long stretches of drift punctuated by step changes on candidacy announcements; the first real information event is the midterms in eleven weeks.
• Ossoff is the name to watch. Third in the nomination book at 15.4% while simultaneously running for re-election to the Georgia Senate seat at 91%. A large November win is the cheapest available catalyst in this field.