James Rosen reports on the online political feud.

President Trump’s public clash with Sen. Bob Corker has exposed a new complication for the commander-in-chief: Lame-duck Republicans who suddenly feel emboldened to tell him how they really feel.

While Trump can threaten certain problematic Republicans with endorsing a primary challenger, the president has little leverage over senators, like Corker, who have announced they’re not seeking reelection.

The Tennessee Republican has essentially been on a no-holds-barred Trump tirade after announcing in late September that he would not seek a third term.

The criticism reached a new level this weekend, as a Twitter war between the two men culminated in Corker doing a 25-minute interview Sunday with The New York Times. In it, he said Trump was treating his presidency like “a reality show” and launching threats at other countries that could put the U.S. “on the path to World War III.”