Michigan Democratic Senate Primary Margin of Victory

Platform comparison

Market context

Michigan’s primary has now cleared, with the market no longer reflecting the live count and the real question shifting to how wide the winner’s edge turned out to be. The only settled benchmark from the last contest was 2024, when Elissa Slotkin won the Democratic Senate primary by a very large 52.6-point margin over Hill Harper, so a landslide is possible in Michigan primaries even when turnout is far below a general election[1].

For this cycle, the late polling backdrop pointed to a much narrower contest. Bloomberg reported on 15 July that a WDIV/Detroit News poll had Haley Stevens ahead of Abdul El-Sayed, 48% to 41%, within the 4.4-point margin of error[5]. Other public polling later in the summer showed El-Sayed leading Stevens, including Emerson’s survey at 54% to 39% with 6% undecided, which helps explain why traders had been pricing outcomes across a wide range rather than one decisive margin band[12][13].

The main catalysts for margin pricing were the final vote count, late absentee processing, and whether the race settled into a two-way or three-way split after Mallory McMorrow remained on the ballot despite suspending her campaign[13]. AP described the race on 4 August as closely watched, and live coverage from CNN that day framed El-Sayed and Stevens as locked in a tight contest[15][17]. In a race with multiple credible polling snapshots and no consistent blowout signal, the margin outcome depends heavily on turnout composition and how much of McMorrow’s vote share persists in the final tally[12][13].

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

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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.

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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.

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.