Texas Republican Senate Primary Winner

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Market context

Texas Republicans are set to choose between Senator John Cornyn and Attorney General Ken Paxton in the 26 May primary runoff, with the winner becoming the party’s nominee for the November Senate election. The race has already taken the shape of an incumbent-versus-insurgent contest, with Cornyn relying on established donor and institutional backing and Paxton leaning on a more hard-right base. That makes this a useful market to frame through turnout rather than simple statewide favourability: in Texas, low- to mid-turnout Republican runoffs can reward the better-organised faction, especially when the electorate is older, more partisan and more likely to show up in a narrow primary calendar.

Recent polling has pointed to a tight finish. The University of Houston Hobby School reported Paxton ahead of Cornyn 48% to 45% among likely runoff voters, with 7% undecided, while earlier primary polling showed Cornyn with a route to force a second-round contest rather than an outright first-ballot win. The key catalyst is the Republican Party’s first official result call after polls close, but traders should also watch for any late endorsements, turnout reports, and whether either side tries to mobilise as a proxy for the wider party divide. If reporting converges quickly, especially on a narrow margin, that may matter more than the initial campaign narratives around Cornyn’s incumbency or Paxton’s legal baggage.

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Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

On PolyGram, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

PolyGram is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What does it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.