Billionaire developer and casino operator Donald Trump said yesterday he will join the Reform Party today and strongly attacked conservative television commentator Patrick J. Buchanan, Trump's potential rival for the party's presidential nomination.

"The Republican Party has just moved too far to the extreme right. The Democrats are too far to the left. I believe the Reform Party can be the true centrist party. And that's very much in line with my thinking," Trump told the Associated Press in saying he will change his Republican voter registration today to the Independence Party, the Reform Party affiliate in New York.

Calling Buchanan "a Hitler lover," Trump said on NBC's "Meet the Press" program, "I guess he's an antisemite. He doesn't like the blacks, he doesn't like the gays. It's just incredible that anybody could embrace this guy, and maybe he'll get 4 or 5 percent of the vote and it'll be a really staunch right wacko vote."

Buchanan, until now a mainstay of the Republican right, has signaled repeatedly that he is likely to switch to the Reform Party today and seek its presidential nomination. The Reform nominee gets $12.6 million in federal funds to campaign and high visibility in the general election, perhaps including participation in televised national debates.

The one factor that could deter him, Buchanan has said, is the prospect of having to fight a Trump candidacy with $100 million to $200 million behind it.

"I believe I can beat Donald Trump head to head as a candidate relatively easily," Buchanan said earlier this month. "Can I beat $200 million or $100 million? I don't know. I doubt it."

In order to qualify for the Reform Party contest, prospective candidates have to get on the ballot individually in a substantial share of the 29 states that do not currently include the Reform Party in general elections.

The process of gaining ballot access can be very expensive, so a wealthy candidate like Trump would have a built-in advantage. As a two-time candidate for the Republican presidential nomination, however, Buchanan could call on past supporters and donors to help him petition to get on ballots.

In many respects, Buchanan and Trump are engaged in the kind of early fencing and maneuvering that takes place in the pre-announcement stage of many political contests. The big difference is that a Trump-Buchanan fight would offer more hostile rhetoric and more ideological conflict than has emerged in the nomination contests of both major parties. Trump, for example, supports abortion rights including late-term procedures; Buchanan supports a constitutional amendment banning abortions.

In a recent fund-raising letter obtained by AP, Buchanan said he intends to bring his stands to the campaign. "Issues which I believe are of profound importance to our nation's future--among them trade, immigration, right to life, our national sovereignty and foreign interventionism--will not be seriously debated in 2000 between the probable establishment nominees," he wrote.

Buchanan has built a strong base within the Reform Party, receiving signals of support or explicit endorsements from such allies of party founder Ross Perot as current chairman Russell Verney and Perot 1996 running mate Pat Choate. In addition, Lenora Fulani, a perennial third-party candidate with strong ties to the left who has recently become a force within the Reform Party, has indicated that she and her allies could back Buchanan.

Trump has been encouraged to run by Minnesota Gov. Jesse Ventura, the Reform Party's highest elected official. Ventura has warned that he may bolt the party if it nominates Buchanan.

"There is a certain controversy to me," the twice-divorced Trump said yesterday. "I am single and I do go out with women and I do respect and adore women and some women love me and probably some women don't, but I am certainly controversial. But I also am a great businessman. I'd make the greatest treaties that this country's seen in a long time."

CAPTION: Donald Trump differs with Patrick J. Buchanan on many issues, which could result in a spirited contest.