Term limits for U.S. House and U.S. Senate. Two terms maximum. Same as U.S. President.

The huge amount of money requied to run for political office can give an appearance of obligated congressional politicians to their donors. By limiting the service to no more than two terms then the control over the elected officials can be reduced . The U.S. President is under such requirement so should the U.S. Congress.
By limiting the ties to donors by those running in office the elected official will be more concerned with the people in their district if they wish to continue for a second term. That would at least be a first step to reform the power structure of political office in the United States of America.