Last week, Republican presidential nominee Donald Trump proposed congressional term limits.

"I hear it from more and more people," Trump said of term limits for federal legislators. "We're going to take a very serious look at that."

The idea of national term limits periodically surfaces as an issue. Republicans campaigned on term limits as part of the 1994 Contract With America platform. The tea party also featured term limits as part of its agenda in 2010. The presidential candidate did not elaborate on a plan. However, the history of term limit proposals indicates there will be difficulties in passage.

In 2012, Congress overwhelmingly rejected an amendment to impose congressional term limits. The next year, a Gallup poll reported that 75% of Americans supported term limits on Congress. However, there is little political movement to limit the number of years congressmen can serve.

Some politicians have run on platforms of voluntary term limits. Tom Coburn of Oklahoma was elected to the U.S. House in 1994 pledging to serve no more than three terms. He honored his pledge and returned a few years later to run for the US Senate. Coburn promised again to serve no more than twelve years.

John Shimkus of Illinois ran for the House in 1996 promising to serve no more than four terms. He is currently in his eleventh term. Shimkus' broken pledge usually surfaces in elections, but has not become a significant factor.

Former US Rep. Ron Paul regularly stated his support for term limits despite serving more than twenty years in the House of Representatives. Paul never imposed voluntary term limits on himself, but introduced legislation for term limits in the 1970s. The libertarian congressman said philosophy of government was more vital than term limits. He said, "If you have a turnover and the same people come in and they believe in big government, nothing good is going to come of it."

Advocates of term limits argue that for term limits to work, they need to be enforceable and apply to everyone.

Critics note that congressional term limits are not a suitable answer for deeper issues of political dysfunction. They cite how lobbyists continually enact influence on novice legislators. Also, gerrymandering ensures parties control certain districts regardless of the length of terms served by candidates.

In 1995, U.S. Supreme Court ruled that Congress and the states cannot impose term limits on the U.S. Congress. Term limits require a constitutional amendment as the 22nd Amendment limits the president to two terms.