Of all the promises made on the campaign trail, President-elect Donald Trump’s vow to pass a constitutional amendment to impose term limits on members of Congress might be the most daunting. Senate Majority Leader Mitch McConnell (R-Ky.) dismissed the idea out of hand the day after Trump’s stunning victory. A few days later, House Speaker Paul D. Ryan (R-Wis.) gave the proposal a tepid endorsement as he indicated it would be up to a House committee to consider Trump’s proposal. The reticence of both Republican leaders on the issue is not surprising, given their long tenures in Congress.