Conservative radio host and former Illinois US Rep. Joe Walsh will challenge President Donald Trump for the Republican presidential nomination in 2020, he announced Sunday.

CNN's John Berman talks to former GOP Congressman Joe Walsh about his op-ed in the New York Times in which Walsh apologizes for his role in getting President Trump elected and suggests the Republican Party needs a primary challenger to Trump in 2020.

Indeed, as the saying goes, politics makes strange bedfellows. The question now is: Do Democrats want to share a "bed" with people who have supported President Donald Trump until recently? The answer should be a resounding yes if Democrats are truly committed to making Trump a one-term president.

Former Republican Rep. Joe Walsh is calling for a primary challenger to take on President Donald Trump in 2020, as he is reckoning with his past controversial comments and apologizing for his role in helping elect an "unfit con man" to the presidency.

It speaks to the total takeover of the Republican Party by Donald Trump that the lingering "Never Trump" movement within the GOP is reduced to trying to pretend they are excited about the idea of Joe Walsh, Mark Sanford or Bill Weld as their banner carrier in next year's presidential primary.

The blue wave that swept the midterm elections in November along with the continuing investigations into President Donald Trump have led to discussions of a potential Republican primary challenge in 2020. Sen. Susan Collins has said a GOP primary would be a good idea, while outgoing Sen. Jeff Flake and Ohio Gov. John Kasich are being talked up as possible contenders.

Anthony Scaramucci, a former White House communications director who has recently withdrawn his support for President Donald Trump, said Monday that he is putting together a coalition of former Trump Cabinet officials to denounce the President ahead of the 2020 election.

Former Massachusetts Gov. Bill Weld announced Monday he is officially entering the race for president, becoming the first Republican to challenge President Donald Trump in the 2020 race.

Something is rotten in the state of Denmark -- but the smell is coming from somewhere else.

CNN's Brian Stelter calls on the media to have more coverage and conversation around President Donald Trump's mental state.