A third-party presidential race by political maverick Ross Perot poses a greater threat to Bill Clinton than to President Bush, according to a new Washington Post-ABC News Poll, and would be particularly damaging to the Arkansas governor in the West.

Nationally, Bush continued to lead both Clinton and Perot when the three men are matched together in a hypothetical test of early voter preferences. According to the poll, 36 percent of all voters surveyed said they would vote for Bush if the election were held today, while 31 percent supported Clinton and 30 percent backed Perot. The remainder were undecided.

Since Perot let it be known in February that he might be a candidate, there has been intense speculation about whom he would most hurt. Last week for the first time Clinton acknowledged that he is the one being hurt by Perot -- a trend confirmed by the new survey -- and voiced his first public criticism of the Texas billionaire.

Yesterday, Vice President Quayle argued that Perot could emerge as Bush's main challenger for reelection, overshadowing Clinton.

"If Ross Perot continues to make steady progress, he could well be our chief opponent this fall," Quayle told a group of reporters in New York. "He's gaining on Bill Clinton every day. . . . He certainly has a full head of steam. He's clearly moving forward."

But Quayle said Perot's presidential fortunes could also go the way of other third-party candidates. "Once he becomes a candidate, things have a way of changing," he said. "He could be a traditional third-party candidate and that is that he sinks once he announces."

There was more good news for Bush in the new survey, which also found that Bush's approval rating has stabilized and may, after a year of virtually uninterrupted decline, be rising.

According to the poll, 43 percent of those questioned said they approved of the job Bush was doing as president, up from 40 percent earlier in the month and 39 percent in March.

There was also good news for Clinton. The survey suggests that the slide in popular support that began in February appears to have stopped.

In the latest poll, 31 percent of those voters surveyed said they supported Clinton over Bush or Perot, up from 29 percent in April.

For Perot, the poll shows that he continues to do especially well with middle-aged voters, independents and those with college degrees. He also enjoys particularly strong support in the West, where he finished well ahead of Clinton in the three-way matchup.

Among westerners interviewed for the survey, Bush was the choice of 42 percent. But Perot easily outdistanced Clinton, finishing with 32 percent compared to the likely Democratic nominee's 23 percent. About one out of five voters lives in the West.

Elsewhere, Clinton does best in the Northeast, where he claims the support of 36 percent of those interviewed, compared to 39 percent for Bush and 19 percent for Perot, his worst regional showing.

In his native South, Clinton trails Bush by 37 percent to 31 percent, with Perot claiming 28 percent.

The Midwest remains a potential battleground. According to the survey, the three candidates are virtually tied, with Bush claiming 34 percent of the vote, Clinton 32 percent and Perot 30 percent.

According to the poll, 49 percent of Perot's supporters said Clinton would be their choice if Perot were not in the race; 38 percent said Bush was their second choice, suggesting that Perot might hurt Clinton more than Bush should he decide to enter the race.

Perot is particularly attractive to potential Clinton voters in the West. Perot's supporters there, when asked to name their second choice, favored Clinton over Bush by 41 percent to 27 percent, easily the biggest difference found in any region of the country.

Perot's support also appears to be surprisingly strong. When asked whether they supported their choice because they liked what he stood for or because they didn't like the other candidates, 56 percent of Perot's supporters said they liked what the Texas native stood for.

Among Bush supporters, 59 percent said they were voting for him because of what he stood for; among Clinton supporters, 49 percent said they backed Clinton because of what he stood for.

Margin of sampling error for the latest poll is plus or minus 3 percentage points for results based on the entire 1,003 sample and 4 percentage points where the attitudes of only registered voters are reported. Interviewing for this survey was conducted April 22-26.

Staff writer John E. Yang in New York contributed to this report.

Telephone interviews of voters show Ross Perot gaining.

GEORGE BUSH

April 26........36%

April 9.........36%

BILL CLINTON

April 26........31%

April 9.........29%

ROSS PEROT

April 26........30%

April 9.........26%

NOTE: Figures do not add to 100 percent because "don't know" is not included. Results are based on a national random sample of 784 registered voters interviewed by telephone April 22-26. April 26 data are from a Washington Post-ABC News Poll and have a margin of sampling error of plus or minus 4 percentage points. Other data are from an ABC News poll conducted by ICR Survey Research of Media, Pa.