I think a way to get terms limits to pass Congress is to anti-grandfather in current members of Congress. So say that all terms limits don’t start counting until the next election and only start counting when someone wins an election. So a Senator elected in 2016 could still run for re-election twice (in 2022 and 2028), even if that Senator had already been in Congress for 40 years (for instance). This would lessen the impact of the term limits on sitting members of Congress and allow terms limits to be phased in.