In the sharpest criticism of President Trump by a senior Republican colleague so far, Senator Mitt Romney of Utah criticized the president on Twitter Thursday night for his continued and hugely unsuccessful efforts to reverse his early electoral defeat of the month against Joseph R. Biden Jr.
Mr. Romney, the 2012 Republican presidential candidate, said the president has exhausted his legal challenges in several battlefield states and tried to challenge the will of voters.
His rebuke against Mr. Trump came the same day the president invited the leaders of the Republican state of Michigan to the White House to discuss their efforts to stop the certification of election results in the state.
“Having failed even to present a plausible case of fraud or widespread conspiracy in court, the president is now resorting to overt pressure on national and local authorities to reverse the will of the people and annul the elections” Mr. Romney wrote. “It’s hard to imagine worse, more undemocratic action from a sitting US president.”
The relationship between Mr. Trump and Mr. Romney has been tumultuous, with Mr. Romney voting alone by a Republican in the Senate to condemn the president of an article of impeachment in February in an otherwise online vote. Mr. Trump was acquitted by the Senate, which is controlled by Republicans.
Mr. Romney wasn’t the only Senate member to suggest Thursday that Mr. Trump should step down.
Senator Ben Sasse of Nebraska said in a statement Thursday night that he revealed that Mr. Trump’s campaign lawyers refused to “actually allege big fraud.”
“Because there are legal consequences for lying to judges,” Sasse said. “President Trump lost Michigan by more than 100,000 votes, and the campaign and its allies lost or withdrew from the five lawsuits in Michigan so they could not produce any evidence.”
Mr Sasse said the efforts of the Trump campaign and Rudolph W. Giuliani, Mr Trump’s personal lawyer, to attack the integrity of the election had caused damage.
“Wild press conferences erode public trust,” Sasse said. “So no, obviously Rudy and his cronies shouldn’t be pressuring voters to ignore their certification obligations under the law. We are a nation of laws, not tweets. “