Russell Verney, Perot's spokesman, said the Texas billionaire decided against running in the primary because he had no intention of actually competing for the White House in the fall against Republican George W. Bush and Democrat Al Gore.

A daylong series of meetings at Perot's office in Dallas included "intense pressure" on Perot to put his name on the ballot in an effort to stop Buchanan, Verney told The Associated Press. Perot resisted such a "negative reason" for running and also felt it would be unethical to seek the nomination but not really run, Verney said.

Besides, Perot, a two-time presidential candidate who turned 70 on Tuesday, would be on only about half the states' ballots in November.

"When you're trying to create a new political party which sets the highest ethical standard, you cannot try to further that goal by unethical actions," Verney said.

Buchanan praised the decision in a statement and said Perot had an "open invitation" to speak at the party's August convention.

"I have great respect for Ross Perot. He is the founder and father of this party," Buchanan said. "Without Ross Perot, there would be no Reform Party, no third choice and there would be no great third-party movement in the 1990s. I wish him well."

Though Perot declined to make a statement on Friday, he is said to be dissatisfied with Buchanan's candidacy. Verney said Perot might make a public statement about his feelings before the party's nominating convention, which will be Aug. 10-13 in Long Beach, Calif.

Perot's supporters, meanwhile, will lobby the party's nominations committee to make "No Endorsement" an option on the primary ballot in order to allow Buchanan opponents to protest his candidacy, Verney said.

Perot's decision comes after longtime supporters, led by Ira Goodman of New Jersey, collected what they said were enough signatures in 18 states to meet the party's rules for putting a candidate on the ballot. Perot had until midnight Friday to accept a spot on the ballot in writing.

It would have been his third presidential campaign on the ticket of the party he founded, after finishing with 19 percent of the vote in 1992 and 8.5 percent in 1996.

He burst onto the political scene in 1992, spending more than $60 million of his own money. Four years later, he spent most of the $29 million he received in federal funds on long-format television time, made an abbreviated campaign swing and never held a news conference.

His showing in 1996 earned the party's 2000 nominee $12.6 million in federal funding for the general election campaign. Had Perot run and won the nomination, he would have used that money to rebuild the party rather than make a vigorous try for the White House.

His decision leaves two candidates who say they have acquired enough support to win spots on the ballot: former Republican Buchanan and Natural Law Party candidate John Hagelin.

In a statement, Hagelin said his own effort made a Perot run unnecessary.

"His candidacy was designed to prevent Pat Buchanan from using the Reform Party as a platform to promote his right-wing social agenda," Hagelin said. "I will vigorously uphold Ross Perot's vision of the Reform Party as a mainstream alternative that will appeal to the 115 million frustrated voters who did not vote in the last election."

Buchanan, who has built a sizable organization around the country, is the front-runner.

Both of those candidacies must be verified Saturday by the party's nominations committee.

If they are, party leaders will mail out primary ballots to party members and any other citizen who requests one. State party chairmen will count the results and announce the winner at the national convention.

Supporters of Buchanan and Perot have been increasingly at odds in the eight months since the conservative commentator left the GOP to pursue the third-party nomination.

Perot's supporters believe that Buchanan has tried to take over the party and move it away from its hands-off approach to social issues. The party platform is silent on such matters as abortion and homosexuality because the party believes government should have no say in such personal issues.

But Buchanan says he's bringing new life into a party riven for years by internal fighting. He has conducted a cross-country campaign to get the party on general election ballots and win enough delegate votes to block any challenge to his nomination. In the process, his supporters have built state parties where none existed and driven out Perot loyalists who tried to block them.