Maine Democratic Senate nominee on July 27?

Platform comparison

Market context

Graham Platner officially withdrew from Maine’s 2026 U.S. Senate race on Wednesday, triggering the Maine Democratic Party’s statutory right to nominate a replacement before the July 27 deadline. This sudden exit, following a sexual assault allegation he denies but which caused top allies to rescind endorsements, has left the party without a candidate in a race pivotal to Senate control. The market’s 1% YES probability reflects the unprecedented nature of this event: no Maine political party has ever replaced its nominee in a general election before, and the compressed timeline—less than three weeks to select a new contender—introduces significant uncertainty about who, if anyone, will emerge as the apparent nominee [1][8].

Historically, similar late-stage nominee withdrawals in high-stakes races have produced chaotic replacement processes, often favouring established insiders over fresh challengers. In Maine’s case, the party has already voted to hold a state convention to pick a replacement, with figures like former Senate president Troy Jackson and Rep. Jared Golden floated as potential candidates, though neither has confirmed interest [3][4]. The catalysts traders must monitor include the party’s announced convention timeline, any formal declarations from potential contenders, and whether the process remains transparent as promised by Executive Director Devon Murphy-Anderson [1][2]. With the settlement window closing 2026-07-27, the next 24–48 hours will determine whether a clear nominee materialises or the race remains in limbo, directly impacting the market’s resolution [1].

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 Prediction Today. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 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 Prediction Today 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.