'I will speak out': Mitt Romney unloads on Trump in Washington Post op-ed days before entering Senate

Mitt Romney won't become a U.S. senator until Thursday, but he's already showing his willingness to stand up to President Donald Trump.

In a new Washington Post editorial, Romney, who won a Senate seat in Utah, discusses the "deep descent" the Trump presidency made in the month of December.

Romney lays out the on-again, off-again nature of his support of fellow Republican Trump, before making the case that "a presidency shapes the public character of the nation," and that Trump is making America a worse place.

"His conduct over the past two years, particularly his actions this month, is evidence that the president has not risen to the mantle of the office," Romney writes. "It is not that all of the president’s policies have been misguided... But policies and appointments are only a part of a presidency."

"The world is also watching" Trump and America's image abroad has been tarnished by Trump, Romney writes.

"To reassume our leadership in world politics, we must repair failings in our politics at home," he writes. "That project begins, of course, with the highest office once again acting to inspire and unite us. It includes political parties promoting policies that strengthen us rather than promote tribalism by exploiting fear and resentment."

Read the full op-ed here.