Utah Republican Sen. Mitt Romney announced Wednesday that he will not run for reelection to the Senate and called for a "new generation of leaders" as he criticized both President Joe Biden and former President Donald Trump.

In a video message, Romney outlined a range of what he described as critical issues, including rising national debt and the climate crisis, and said "neither President Biden nor former President Trump are leading their party to confront those issues."

Romney has long been a rare member of the Republican party who has been an outspoken critic of Trump.

At a time when the age of prominent politicians on both sides of the aisle has come under increasing scrutiny, Romney also emphasized the need for a new generation of leadership.

"At the end of another term, I'd be in my mid-80s," Romney, who is 76, said. "Frankly, it's time for a new generation of leaders. They're the ones that need to make the decisions that will shape the world they will be living in."

"While I'm not running for re-election, I'm not retiring from the fight," Romney said, after criticizing both President Biden and former President Trump for failing to provide solutions to issues like the national debt and global warming. "I'll be your United States Senator until January of 2025."

This story has been updated with additional details.