Republicans, who made Nancy Pelosi into a successful boogeyman for their base, are now trying the same tactic with one of their own: Mitch McConnell, the Senate majority leader.
President Trump’s tentative deal with Democrats has elevated the one issue that most fiercely divides Republicans, threatening the party’s broader agenda.
President Trump came under sharp attack on Thursday for appearing to set aside a border wall fight while reaching a deal on DACA immigrants.
Many Republicans believe President Trump may have made it inevitable that the G.O.P. will rupture and spawn a third party.
President Trump’s reluctance to single out the far right reflects a view widely held by conservatives that the news media willingly overlooks left-wing extremism.