Rival Republican presidential candidates said yesterday they welcome Texas Gov. George W. Bush's decision to gamble on winning the Aug. 14 Iowa straw vote -- even though some of them admit they run at least as much risk of being embarrassed by the results.

Bush's declaration Saturday, his first day of stumping in Iowa, that "I think we not only ought to compete, I think we ought to go win the Ames straw poll," had the immediate effect of raising the stakes for everyone in the quadrennial event the state Republican Party runs to raise money and heighten interest in February's caucuses.

Brian Kennedy, a former Iowa GOP chairman who heads Lamar Alexander's campaign, said he was surprised that Bush chose to test his strength this early and "on a field where his competition is strongest." A victory could solidify Bush's standing atop the GOP field, but a loss would knock much of the luster off his reputation as the best bet to lead Republicans back to the White House.

Bill Dal Col, campaign manager for Malcolm S. "Steve" Forbes, said Bush had no choice. "With all the hype he has created, he has to win it -- and win big," Dal Col said.

Iowa GOP Chairman Kayne Robinson said the event in Ames is expected to draw 10,000 to 12,000 people -- a fraction of the number likely to turn out next winter for the Iowa caucuses, which traditionally have led off the national delegate-selection process. She said the straw vote has been a fairly reliable predictor of caucus results, because "no one who finished out of the top three in Ames has won the caucuses."

Attendance this year will be limited to Iowa residents, a break from the past when campaigns could bring in outsiders. The registration fee of $25 a head often is paid by the campaigns, which mount phone banks and run buses to transport people to Ames.

Bush has outdistanced his rivals in fund-raising, but he is the last to reach Iowa for campaigning. Forbes, who is financing much of his race with his own checkbook, can match or exceed Bush in paying for a massive effort to get Iowans to the mid-August event.

The straw vote is regarded as essentially an organizational test, and Robinson said Bush -- despite the late start on his campaigning -- ranks with Alexander, Forbes and conservative activist Gary Bauer in having organizers "in substantially every county."

Alexander may have even more at stake in Ames than Bush, several observers said. The former Tennessee governor has spent 50 days campaigning Iowa since the last election, in which he finished third behind Robert J. Dole and Patrick J. Buchanan in the caucuses. He plans to spend 24 more days there, including visits to 60 counties, before the Ames voting, said his Iowa manager, David Kochel.

With Alexander acknowledging that his fund-raising has dwindled because of Bush's lead in national polls and that he regards Iowa as the crucial test of his political viability, Dal Col said: "A win in Ames is critical for Alexander to stay alive, just as it is for Bush to sustain those elevated expectations."

But Kochel said that as long as Alexander finishes in the top three, he will be satisfied.

Bauer's chances, several sources said, look better in the straw vote than his meager standing in national polls would suggest, because of his early success in enlisting Christian conservatives who share his strong antiabortion stand. The appeal that Bauer and another ardent antiabortion speaker, Alan Keyes, have demonstrated in that constituency threatens Buchanan and former vice president Dan Quayle, who rank higher in national polls.

Elizabeth Dole has inherited some of the organizational support that helped her husband to Iowa victories, but a spokesman conceded that the Ames event will test "if the crowds she has drawn in Iowa are real." Monte Shaw, who was active in previous Dole campaigns and is managing the former Red Cross president's effort, said he looks for "a credible showing" in Ames.

Within the Bush camp, strategists said the goal is to win in Ames. But competing in the straw vote also provides a way to motivate Bush supporters, who otherwise would be idle in the eight weeks before Ames, and to field-test his organization before the February caucuses, where the results count in winning delegates.

Staff writer David Von Drehle contributed to this report.