Utah Republican Sen. Mitt Romney said Wednesday that he will not run for reelection, ending a storied two-decade political career that included the 2012 Republican GOP nomination for president and a term as Massachusetts governor.

Romney, 76, said the country’s many challenges call for a younger generation of leaders. He said the U.S. would be better served if the two front-runners for their parties’ 2024 presidential nominations — Democratic President Joe Biden and Republican former President Donald Trump — stepped aside. Biden is 80 and Trump is 77.

“The times we’re living in redemand the next generation step up and express their point of view and to make the decisions that will shape American politics over the coming century,” Romney said in a news conference at the Capitol. He said baby boomers like him are “not the right ones to be making the decisions for tomorrow.”

He said after he leaves the Senate he plans to focus on getting more young people voting and involved in the political process.