Maine Democratic Senate nominee on July 27?

Platform comparison

Market context

Graham Platner, Maine’s Democratic nominee for the 2026 U.S. Senate, suspended his campaign on 8 July after a former partner accused him of sexual assault in 2021, a claim he denies. This withdrawal occurs just before the state’s 13 July deadline for candidates to exit the ballot, triggering the Maine Democratic Party’s two-week window to appoint a replacement by 27 July. The party has already voted to hold a nominating convention to select a new nominee, with Charlie Dingman, the state party chair, overseeing the process [1][2][5].

Historically, sudden nominee withdrawals in high-stakes Senate races—such as 2018’s Georgia Democratic primary or 2020’s Nevada Senate contest—have rarely resulted in immediate replacement success, often due to compressed timelines and internal party friction. In those cases, the new nominee’s viability depended heavily on pre-existing establishment backing and rapid consensus-building. With only 14 days to convene a convention and no established replacement procedure, the 1% crowd-implied probability on the “Maine Democratic Senate nominee on July 27?” market reflects deep uncertainty about whether a credible candidate will emerge before the deadline [1][3][5].

Traders should monitor three key catalysts: the official date and location of the nominating convention, the list of declared candidates stepping forward to vie for the nomination, and any public endorsements from top Maine Democrats. Recent reporting from CNN confirms that multiple Democrats have already expressed interest in replacing Platner, but the party’s ability to unify behind one figure remains unproven [1][11]. The settlement window ends 27 July at 23:59 UTC, making the next 18 days critical for determining whether the market’s 1% YES probability will shift as the convention unfolds [1][2].

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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Best Prediction Markets. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

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