GOP leadership is firmly not behind Trump right now. Trump's behavior is also a risk to the future of the Republican party, so [...]
In 2016, Trump was supposed to be the challenger for Americans who distrusted the GOP after
decades of being betrayed by them. He has always been disliked by the corrupt career-politician GOP leadership, and especially by the neocons. It was as much an upset for him to win the party nomination as it was for him to win the general election; but the GOP leadership had no choice but to go along, because Trump was overwhelmingly popular.
In 2016, Trump was widely thought as the
only person who could lose to Clinton in the general election. GOP leadership was afraid of losing the House, Senate and Presidency if Trump was nominated. In 2016, none of this turned out to be true, but the House was lost in 2018, and the Senate and Presidency were lost in 2021/0.
I think Trump lost in 2020 because he made the election a referendum on himself. Trump has consistently been less popular personally than his policies. Ditto with his tweeting, his personal attacks on his critics, and the chaos that he caused. I don't think Trump had the right people helping him at the top of his reelection campaign.
With there being a day and a half left in Trump's Presidency, I don't think he is going to be removed from office via the 25th amendment.