Some voters, though, think we should have clearer rules about when a politician is too old to serve. Sixty-seven percent of respondents strongly or somewhat supported an age limit for serving in the Senate in a YouGov/UMass Amherst poll from June, and 58 percent of adults thought age limits for serving as president would be a good idea in a Marist poll from last November. Sixty-eight percent of respondents favored mental competency tests for candidates over 75 in a YouGov/Yahoo survey from February. A plurality, 48 percent, think the job of president is too demanding for someone over 75, according to a CBS/YouGov poll from June. And overall, Americans’ preference for younger leadership is clear: About half of Americans think the ideal age for a president is someone in their 50s, according to the Pew Research Center.