WASHINGTON — President Trump has revived unproven voter fraud allegations, telling a group of senators in a private meeting Thursday that he lost New Hampshire last November because thousands of Massachusetts residents were bused to the neighboring state to cast ballots against him.

The president offered no evidence to support the claim. New Hampshire’s secretary of state, who is in charge of elections in the state, disputed the president’s claims, as did the state’s two US senators, and on Friday night a member of the Federal Election Commission called on Trump to release proof of his charge.

Trump also said that illegal voting was part of the reason former senator Kelly Ayotte, a Republican, lost. An aide to Ayotte said that she does not believe she lost because of voter fraud.

The claims were made while Trump was meeting in the White House with a bipartisan group of senators. The conversation is further evidence that Trump continues to be focused on the election, which he won despite losing the popular vote to Hillary Clinton by nearly 3 million votes.