Maine Democratic Senate nominee on July 27?

Platform comparison

Market context

Graham Platner has suspended his Maine Senate campaign following a sexual assault allegation, clearing the way for the Maine Democratic Party to select a new nominee before the July 27 deadline. This real-world shift means the current 1% YES price on Polymarket for the contract titled "Maine Democratic Senate nominee on July 27" reflects a market betting that the party will not formally replace him, or that the replacement process will fail to produce an apparent nominee by the settlement time. On-chain, this contract trades USDC on the Polygon network using conditional tokens, where the payout hinges entirely on whether an official party announcement identifies a new candidate before 11:59 PM ET on July 27.

Historically, sudden nominee withdrawals in high-stakes Senate races rarely result in immediate replacements without significant internal party friction, especially when the original candidate won the primary with 72% of the vote [7]. Comparable cases show that parties often delay selecting a replacement until legal or procedural hurdles are resolved, and the Maine Democratic Party has admitted there is no established procedure for filling such a vacancy [5]. The 1% probability aligns with this precedent, suggesting traders expect the party to struggle to convene a convention or agree on a candidate within the two-week window, rather than swiftly appointing a successor.

Traders should monitor the Maine Democratic Party’s scheduled nominating convention and any official statements from party chair Charlie Dingman regarding the replacement timeline [1]. The party voted on July 8 to hold a convention to select a new nominee if Platner steps aside, but the lack of a clear procedure creates uncertainty [6]. Recent reports confirm Platner intends to exit the race before the July 13 withdrawal deadline, triggering the party’s two-week window to act [1]. Key dependencies include whether the convention is successfully convened and whether a candidate is formally announced before the settlement deadline, as any delay could invalidate the YES outcome.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.