Moderate Republican Rep. John Edward Porter (Ill.) surprised colleagues yesterday and announced that he will not run for reelection.

"This is simply the right time to move on," Porter said, adding that "a factor" in his decision was a House GOP rule requiring committee and subcommittee chairmen to relinquish their posts after six years. Porter is chairman of the Appropriations subcommittee on labor, health and human services, and education.

Porter fought many of the GOP cuts in social programs in recent years. Yesterday he cited his support for human rights, biomedical research and family planning as his proudest congressional achievements.

An ally of House Speaker J. Dennis Hastert (R-Ill.), Porter is the second Illinois Republican to announce his retirement in less than a week. Rep. Thomas W. Ewing, Hastert's best friend in Congress, said last week that he will step down next year.

While Ewing's district is safely Republican, Democrats are eyeing the possibility of taking over the 10th District, which was represented by liberal Democrat Abner J. Mikva until Porter won the seat in a special election in 1980. The northern suburbs of Chicago make the district Illinois' wealthiest, and Bill Clinton won it in 1996 after losing it narrowly to George Bush in 1992.

"It's a very independent district," Porter said, though he predicted that another socially moderate, fiscally conservative Republican would succeed him.

Buchanan Delays His Big Decision

Patrick J. Buchanan has postponed until the end of the month his self-imposed deadline of Friday to announce whether he will bolt the Republican Party to seek the Reform Party's presidential nomination.

Aides did not give Buchanan's reason for delaying his decision. But he has openly discussed his worry that Donald Trump, mega-millionaire developer and casino magnate, could spend huge sums on the contest for the Reform nomination. Trump recently formed an exploratory committee and expressed strong interest in running.

The Reform Party's nominating rules favor those who have financial resources or large mailing lists of supporters.

To qualify to run for the nomination, a candidate must get on the ballot in most of the 29 states that do not give the Reform Party a line in the 2000 general election. That requires extensive signature-gathering, which can be costly unless a candidate already has a large volunteer base.

Once qualified, candidates compete by getting the support of Reform Party members and, more important, by getting supporters who are not members to request and then mail in ballots. The winner of this wide-open contest secures the nomination and the $12.6 million in federal money that goes with it.

Staff writer Thomas B. Edsall contributed to this report.