The Supreme Court ruled in 1955 that states cannot impose additional qualifications on their federal representatives, including term limits, beyond those provided by the Constitution of the United States (see U.S. Term Limits, Inc. v. Thornton, 514 U.S. 779).

Therefore, if an elected U.S. Representative is limited to three terms in office, it must either be self-imposed or a U.S. Constitutional Amendment is needed.

Few U.S. Representatives will self-impose term limits. Tom Coburn did. He served three terms as Oklahoma U.S. Representative (1994-2000), kept his promise, and did not run for a fourth term.

My incumbent opponent, Oklahoma District 3 Congressman Frank Lucas, has also expressed his support for term limits. He cosponsored a bill calling for a Constitutional Amendment that would cap elected U.S. Representatives to three terms. Frank Lucas is now running for his fifteenth term.

Original source can be found here.