After a quick rise in the race for the Republican presidential nomination, Texas Gov. Rick Perry has experienced an almost equally dramatic decline, losing about half of his support over the past month, according to a new Washington Post-ABC News poll.

Perry's slide, which comes after several uneven performances in candidate debates, has allowed former Massachusetts Gov. Mitt Romney to resurface atop the GOP field. But the most direct beneficiary is businessman Herman Cain, now tied for second.

The rapidly changing fortunes underscore the fluidity of the Republican race, in which some major donors and party leaders are now urging New Jersey Gov. Chris Christie to declare his candidacy.

Among announced candidates, Romney leads with 25 percent, identical to his support a month ago, among Republicans and GOP-leaning independents. Perry and Cain are tied for second at 16 percent -- a 13-point drop for Perry and a 12-point rise for Cain since early September.

Rep. Ron Paul of Texas is at 11 percent, followed by former House Speaker Newt Gingrich and Rep. Michele Bachmann of Minnesota, both at 7 percent; former Sen. Rick Santorum of Pennsylvania, at 2 percent, and former Utah Gov. Jon Huntsman Jr., at 1 percent.

The telephone poll was conducted Sept. 29 to Oct. 2 among a random national sample of 1,002 adults. The margin of error was 6 points for the sample of Republicans and GOP-leaning independents.

WASHINGTON POST