Members of Congress may seek additional terms beyond their initial terms, but must win new terms by 60%, plus 1 vote or more. The 60%, plus 1 rule would also apply to House members seeking Senate seats and Senators running for the House. Candidates for President and Vice-president would not be subject this 60% plurality since the number of terms they may serve in those positions is already limited by the Constitution.
Incumbents who truly accomplish the goals set by and for their constituents should welcome the potentially higher approval rate from voters in their districts. However, if the job is not being done, voters will have new leverage under law to make changes. There is some precedence for this in the Super Majority votes in Congress already in use.