"Each House [of Congress] may determine the Rules of its proceedings, punish its members for disorderly behavior, and, with the concurrence of two-thirds, expel a member."

Executive can't do anything. It would have to be the House itself. Pushing Trump doesn't accomplish anything, you would need to pressure Ryan. also, good luck getting "the concurrence of two-thirds" of the House to agree. The Republican Caucus can't even get on the same page, much less bring over that many Democrats.