Maine Gov. Janet Mills (D) announced on April 30 that she would suspend her campaign for the Democratic nomination for U.S. Senate, becoming the first governor to do so since 1988. In a statement, Mills said, “While I have the drive and passion, commitment and experience, and above all else — the fight — to continue on, I very simply do not have the one thing that political campaigns unfortunately require today: the financial resources.”

Mills is the first governor running for Senate to withdraw from the primary since 1988. The most recent governor to do so was Reuben Askew (D-Fla.) in 1988. In Ballotpedia’s coverage going back to 1914, only seven governors have withdrawn their primary bids before the election. Many of these withdrawals occurred in the period of 1918-1930, when four governors withdrew their candidacies. After 1930, the next time this occurred was in 1984, 54 years later. Mills is the first governor in the 21st century to withdraw a bid.

When counting the outcomes of governors running for Senate, Ballotpedia treats withdrawals as a unique circumstance. Other unique circumstances include three governors losing via nominating conventions rather than a primary, three governors losing the primary, becoming the general election nominee through stranger circumstances and losing the general election, three governors winning the nomination and dying and being replaced before the general election, and one governor winning posthumously. The most recent other outcome before Mills' withdrawal was in 2000, when Gov. Mel Carnahan (D-Mo.) died in a plane crash on October 16, 2000, after the deadline to replace a candidate had passed, and won the election that November. His wife, Jean Carnahan (D-Mo.), was appointed to the seat.

With Mills’ withdrawal, David Costello (D) and Graham Platner (D) are running for the Democratic nomination. The winner will face incumbent Susan Collins (R), who was first elected in 1996. Ballotpedia considers the general election as one of 11 battlegrounds it is covering in 2026.

To read more about U.S. Senate battlegrounds, click here. To read more about Ballotpedia’s coverage of governors running for U.S. Senate, click here.