Tenure
Shortly before assuming office, Romney wrote a Washington Post editorial strongly criticizing Trump's character. Ronna McDaniel, Romney's niece and the chair of the Republican National Committee, called his comments "disappointing and unproductive", while Trump wrote that he "[w]ould much prefer that Mitt focus on Border Security and so many other things where he can be helpful". By November 9, 2019, Romney was just one of three Republican senators, along with Susan Collins of Maine and Lisa Murkowski of Alaska, who declined to co-sponsor a resolution opposing the impeachment inquiry process into Trump. He was one of two Republicans (with Collins) who joined all Democrats voting to allow impeachment witnesses.
Romney condemned the 2019 Sri Lanka Easter bombings, saying: "As we celebrate the miracle of Easter, we hold in our hearts the victims of the senseless violence in Sri Lanka and their loved ones."
After many called for Representative George Santos to step down after being investigated by the House Ethics Committee, Romney confronted Santos during President Biden's 2023 State of the Union Address, saying he "shouldn't be in Congress".
In the October 2019 issue of The Atlantic, Romney revealed that he used a secret Twitter account to keep tabs on political conversation there, saying, "What do they call me, a lurker?" Shortly thereafter, Slate found a Twitter account with the name Pierre Delecto. The account was registered in July 2011, followed about 700 people, and had eight followers at the time it was discovered. It had tweeted 10 times, always in reply to other tweets. The next day, Romney confirmed ownership of the account.
On February 5, 2020, after Romney read a prepared text on the Senate floor decrying "corrupting an election to keep oneself in office" as "perhaps the most abusive and destructive violation of one's oath of office that I can imagine", he broke ranks with the Republican majority as the sole Republican senator to vote to convict Trump in his first impeachment trial, thereby becoming, according to press reports, the first U.S. senator in United States history to vote to convict a president of the same political party.
Fallout from the vote included Romney's being formally censured by various Republican organizations outside of Utah; in comparison, anger against Romney among Republicans within Utah was more muted, and his impeachment vote, according to opinion polling, was supported by Utah Democrats. Jason Perry, director of the University of Utah's Hinckley Institute of Politics, said, "Democrats in Utah were more excited about Mitt Romney's vote than [Utah] Republicans were disappointed." Republicans for the Rule of Law ran various ads thanking Romney.
On June 7, 2020, in response to the murder of George Floyd and the worldwide protests against police brutality, Romney became the first Republican senator to participate in a protest alongside Black Lives Matter. He said, "We need many voices against racism and against brutality, and we need to make sure that people understand that Black Lives Matter." This act drew praise and admiration from the left and right, with some Republicans questioning why other congressional Republicans were not showing support for the movement. On Twitter, Senator Kamala Harris praised Romney's actions, saying, "We need more of this." Trump mocked Romney, saying, "Tremendous sincerity, what a guy. Hard to believe, with this kind of political talent, his numbers would 'tank' so badly in Utah!"
Romney did not endorse Trump's 2020 reelection campaign and told reporters that he did not vote for him. In a Washington Post op-ed, Romney wrote that Trump "has not risen to the mantle of the office". After the victory of Joe Biden and his running mate, Kamala Harris, Romney was the first Republican senator to extend his congratulations to them.
On the morning of January 5, 2021, Romney was heckled and harassed at the airport on his way to Washington, D.C., to certify Joe Biden's election win in the Senate. Cellphone footage of the incident showed Trump supporters accusing Romney of not supporting Trump's baseless claims of election fraud, and chanting "Traitor! Traitor! Traitor!" as Romney boarded his flight.
On the morning of January 6, protesters assembled at the "Save America" rally on the Ellipse, where Trump, Donald Trump Jr., Rudy Giuliani, and several members of Congress addressed the crowd fueling the conspiracy theories about election fraud. Later that day, while the Senate was in session certifying the 2021 United States Electoral College vote count within the United States Capitol, hundreds of Trump supporters violently attacked the Capitol, where they looted senators' offices and broke into the chamber of the United States Senate. Police evacuated the senators and Vice President Mike Pence to an undisclosed area. As they were evacuating Romney, he yelled at Ted Cruz and other Republican congressmen, "This is what you've gotten, guys!" According to New York Times reporter Jonathan Martin, Romney told him with "fury in his voice", "This is what the president has caused today, this insurrection!" Romney fully rebuked Trump and condemned the actions of the attackers. Later that night, when Congress had reconvened, Romney said on the Senate floor:
We gather today due to a selfish man's injured pride and the outrage of his supporters whom he has deliberately misinformed for the past two months and stirred to action this very morning ... Those who choose to continue to support his dangerous gambit by objecting to the results of a legitimate, democratic election will forever be seen as being complicit in an unprecedented attack against our democracy ... They will be remembered for their role in this shameful episode in American history. That will be their legacy…The best way we can show respect for the voters who are upset is by telling them the truth! That is the burden, and the duty, of leadership. The truth is that President-elect Biden won the election. President Trump lost. I've had that experience myself. It's no fun.On February 10, 2021, new video was released during Trump's second impeachment trial that showed capitol police officer Eugene Goodman saving Romney from running into the Capitol rioters. During a break in the hearing, Romney said, "It was very troubling seeing the great violence the capitol police were subjected to." Romney also said he didn't know how close he was and didn't know it had been Goodman who diverted him away from the rioters, but that he looked forward to thanking Goodman.
On May 27, 2021, along with five other Republicans and all present Democrats, Romney voted to establish a bipartisan commission to investigate the January 6 attack. The vote failed for lack of 60 required "yes" votes.
On January 13, 2021, the House voted to impeach Trump a second time for incitement of insurrection. On January 26, Republican senator Rand Paul of Kentucky introduced a motion to dismiss the impeachment charge. The objection was defeated on a 55–45 vote; Romney was one of the five Republicans to vote against it.
On February 13, 2021, Romney and five other Republican senators voted to allow other witnesses in the impeachment trial. Later that day Romney voted to convict Trump for the second time along with six of his Republican colleagues. The final vote was 57 to convict and 43 to acquit. He wrote a statement that read in part:
President Trump attempted to corrupt the election by pressuring the Secretary of State of Georgia to falsify the election results in his state. President Trump incited the insurrection against Congress by using the power of his office to summon his supporters to Washington on January 6th and urging them to march on the Capitol during the counting of electoral votes. He did this despite the obvious and well known threats of violence that day. President Trump also violated his oath of office by failing to protect the Capitol, the Vice President, and others in the Capitol. Each and every one of these conclusions compels me to support conviction.
In December 2025, Romney expressed in a New York Times editorial that the affluent must contribute more in taxes to tackle the escalating national debt. He argued that merely reducing spending is insufficient, and to avert the United States from approaching a "fiscal cliff", it is essential to manage both expenditures and revenues—this includes increasing taxes on the wealthy. He has proposed that certain significant exemptions and "tax loopholes" should be eliminated.