ASHINGTON - Time was when Republicans shuddered at the thought of Reform Party candidate Patrick J. Buchanan undercutting the political support of George W. Bush in this fall's presidential race, indirectly handing a victory to Al Gore.
Yet Democrats have also been focusing on a different third-party candidacy, the Green Party's Ralph Nader, highlighting the stakes for both sides this election.
The small but geographically diverse political support for Nader - up to 9 percentage points in one poll in California, a key state for the vice president - has some liberals wondering whether the longtime consumer advocate will sap strength from their traditional ally, the Democratic Party.
Their fear is that Nader's candidacy could take away enough votes from Gore to elect Bush, the Republican governor of Texas, bringing a conservative philosophy to the White House. They believe that would threaten not only the environmental and trade policies Nader is espousing on the stump, but also other liberal causes such as abortion rights, civil rights, gay rights, and shaping the ideological tilt of the Supreme Court.
Representative Barney Frank, Democrat of Newton and an openly gay member of Congress, has taken to sounding the alarm in op-ed comments and recent speeches. That triggered a rebuke from Nader, who last week said: ''Sometimes he talks faster than his brain operates.''
Others understand Frank's concern, even if they do not currently share his sense of urgency about the consumer activist. Among them is Alice Germond, executive vice president of the National Abortion and Reproductive Rights Action League.
''What is troublesome about Nader from our perspective is that he is suggesting Gore and Bush are similar and that's why people should vote for him,'' Germond said. ''On the issue of choice, ... the two are 180 degrees apart.''
She notes that Gore favors abortion rights, while Bush opposes abortion except in cases of rape, incest, or when the life of a baby's mother is threatened. Bush has also said the Supreme Court's 1973 Roe v. Wade decision legalizing abortion ''overstepped the constitutional bounds,'' while Gore has said he supports the ruling.
''I fear that sometimes this simplistic rhetoric can take hold if people aren't paying attention to the issues, so I am always worried when somebody who is running for the highest office in the nation is making statements that aren't true and then expects himself to be taken seriously, as Ralph Nader does,'' Germond said.
Amy Isaacs, executive director of Americans for Democratic Action, a liberal organization, said she is ''concerned, yes, panicked, no,'' that Nader may influence the outcome of a Bush-Gore matchup.
Her major worry is how the next president will shape the balance of the Supreme Court, since as many as four justices could retire during his term.
''More than anything else, that has the potential for resonating for generations,'' Isaacs said. ''Other policy can be turned around sooner.''
Isaacs said she takes solace in political history, which shows that third-party candidates often flower when they are a novelty but wilt under sustained scrutiny.
''I think that most of those who are taking a look at Mr. Nader are going to say this election is too important for feel-good or protest politics, and that's the reason I'm not panicked,'' she said. ''I think that ultimately what I view as common sense will prevail, and these people will end up voting for Al Gore.''
Nader, 66, a native of Winsted, Conn., burst onto the public scene in 1965 with his book indicting General Motors' safety record, ''Unsafe at any Speed.'' He has gone on to found an array of public interest groups.
Today he says he wants to eliminate the ''democracy gap'' and make it easier for outsiders to challenge the two-party system. He supports free trade, strong unions, and universal health care. He also has said he would raise gas taxes and replace Alan Greenspan as Federal Reserve chairman.
Frank recently warned about the impact of Nader's candidacy on liberal causes during a speech before Americans for Democratic Action. He also complained about Nader during a keynote address at the Democratic state convention in Wisconsin.
Last week, he did so again on the op-ed page of the Globe.
''The Nader argument is based on the assumption that there is no important difference between Al Gore and George Bush that justifies a vote for Gore,'' the congressman told columnist Thomas Oliphant. ''Well, we know for an absolute fact that Gore and Bush differ completely on abortion rights, on gay rights, on controlling gun violence, to pick just three examples. ... He has never spoken out on these matters.''
That prompted a response from Nader during a speech last Tuesday at the National Press Club.
While acknowledging his roots as a consumer and environmental activist, Nader told his audience: ''I've been an advocate for civil liberties when he was trying to figure out how to play soccer in elementary school, and I don't need to be lectured by him about this.''
During an interview, Frank laughed at the criticism, saying, ''Ralph has never been really in touch with American culture; they did not play soccer in Bayonne, N.J., when I was growing up. There was a lot more stickball, as I recall.''
Substantively, he said that Nader is ''trying to appeal to the left, but it's hard to appeal to the left while ignoring these other issues.''
Instead, Frank said Nader's true goal is to defeat Gore. ''If you accomplish that, you get the Supreme Court moving in a conservative direction,'' Frank said. ''Clinton has also vetoed antiabortion legislation, pushed for gun legislation. Those things would go away if Bush is elected president.''
Nader, in an interview last week, said, ''If you look at it from Barney's viewpoint, he should welcome as much progressive effort as possible to sharpen and hone these issues on behalf of the Democratic Party. The Democrats are taking these constituencies for granted.''
Then turning more blunt, Nader said: ''I think Barney is being used as a surrogate for those too cowardly to debate me.''
Winnie Stachelberg, political director for the Human Rights Campaign, a leading gay and lesbian group, said she expects the gay community to support the vice president, no matter what the polls say about Nader right now.
''I think it's early and polls are fluctuating day to day, but I think the gay and lesbian community is savvy enough to want results and see results and that's what, I think, Al Gore has delivered,'' she said.
