SALT LAKE CITY — With Mitt Romney set to exit the U.S. Senate, Washington will be without one of its strongest conservative critics of Donald Trump when the president retakes the White House in the new year.

The retiring senator will reflect on his two-decade political career, which included the 2012 Republican presidential nomination, a term as Massachusetts governor and several skirmishes with Trump loyalists in Congress, at a final news conference Friday in Salt Lake City.

Romney, 77, chose not to run for reelection this year after representing Utah in the Senate since 2019. He has said he wants to focus on getting more young people involved in politics after he leaves office in January but has not shared specific plans.

Once the standard-bearer of the Republican Party, Romney watched his brand of moderate conservatism shift from establishment to outlier as Trump took hold of the party.

He soon became the voice of Congress’ centrist core, leading negotiations for the $550 billion bipartisan infrastructure law — one of the Biden administration’s crowning achievements — and a major COVID-19 relief package.

Political observers worry his departure may create a vacuum of strong centrist voices who can keep bipartisanship alive at a time of increased polarization in Washington.

Romney will be succeeded in the Senate by Republican U.S. Rep. John Curtis, who has developed a reputation for pushing back against party leaders such as Trump who falsely claim climate change is a hoax. Eyes will be on Curtis and other moderate Republicans who might break with the party in votes to confirm Trump’s cabinet picks.

In 2020, Romney became the first senator in U.S. history to vote to convict a president from their own party in an impeachment trial. He was the sole Republican in Congress to vote to convict Trump at his two impeachment trials. Trump was acquitted by the Senate both times.

Earlier this year, Romney pledged not to vote for Trump but declined to join some other high-profile Republicans in endorsing Democrat Kamala Harris, saying he wanted to preserve his future ability to help rebuild the Republican Party.