How many 2026 US Senate races will Democrats win in states Donald Trump carried by 10 points or more in 2024?

My most likely prediction for the number of Democratic Senate wins in states Donald Trump carried by 10 points or more is 3 races because favorable September polling across key battlegrounds is tempered by prediction market odds favoring Republicans in states like Iowa and Kansas.

This question resolves to the number of US Senate elections held in 2026 that are won by a Democratic candidate in states where Donald Trump's margin over Kamala Harris in the 2024 presidential election was 10.00 percentage points or more.

Definitions:

• Elections covered: all regular and special US Senate elections held on 3 November 2026, including any runoff for those seats held by 31 January 2027 (the runoff result then determines the winner).
• Trump's 2024 margin: Trump's share of the total presidential vote minus Harris's share in that state, per certified 2024 results as compiled by the Federal Election Commission ('Federal Elections 2024'), or the state's certified results if the FEC compilation is unavailable.
• Democratic candidate: the Democratic Party nominee; in states without party nominations (e.g. top-four or jungle systems), a candidate listed on the ballot with a Democratic party designation; or an independent who publicly announces, by 3 January 2027, that they will caucus with Senate Democrats.
• The winner is the candidate certified as elected by the relevant state authority. If certification is pending on 31 January 2027, the Associated Press projection is used.

If both seats in a state are contested and both are won by Democrats, each counts separately.