Five years after he defeated former House speaker Thomas S. Foley (D-Wash.) with a promise that he would serve only three terms, Rep. George R. Nethercutt (R-Wash.) has declared that he has changed his mind and will run for a fourth term.

The leading advocacy group for term limits immediately declared that it would spend as much as $1 million on a campaign to defeat Nethercutt, and Democrats claimed that the incumbent's decision to break his promise may make the seat very competitive.

The prospect of a tough fight, however, did not deter Nethercutt.

"I've changed my mind," Nethercutt said at a news conference Sunday in Spokane, according to the Associated Press. "I made a mistake when I chose to set a limit on my service." Nethercutt defended his change of heart, saying: "The only people who don't change their minds are in cemeteries and insane asylums."

Republican leaders in both his home state and on Capitol Hill have urged Nethercutt to break his term limit promise. They believe the GOP is more likely to hold the seat if he is the candidate.

Nethercutt's self-imposed term limitation was crucial to his razor-thin margin over Foley in 1994, when Nethercutt won by just 3,983 votes out of over 215,000 cast. He portrayed Foley as a career politician who had served so long that he was enmeshed in the interest group politics of the nation's capital.

Nethercutt's decision infuriated the leading proponent of term limits, U.S. Term Limits, which plans to launch a round of negative advertising in an effort to defeat Nethercutt.

U.S. Term Limits has a mixed record running negative campaigns against incumbents. Democrats, however, said that the large sum to be spent attacking Nethercutt will benefit the Democratic nominee. A number of local Democrats are considering the race, including State Rep. Jeff Gombosky, State Sen. Lisa Brown and Bill Etter, an attorney.

"We believe he is beatable," said Erik Smith, communications director for the Democratic Congressional Campaign Committee. The normal rule of thumb is that it is easier to take over an open seat than to beat an incumbent, but Smith said, "this may prove to be the exception to the rule."

In addition to Nethercutt, Reps. Scott McInnnis (R-Colo.) and Martin T. Meehan (D-Mass) have declared they are abandoning self-imposed term limits.

CAPTION: Rep. George R. Nethercutt's (R-Wash.) decision may add to competition.