WASHINGTON – And the leading Republican presidential candidate is … none of the above.

The latest Associated Press-Ipsos poll found that nearly a quarter of Republicans are unwilling to back top-tier hopefuls Rudy Giuliani, Fred Thompson, John McCain or Mitt Romney, and no one candidate has emerged as the clear front-runner among Christian evangelicals. Such dissatisfaction underscores the volatility of the 2008 GOP nomination fight.

In sharp contrast, the Democratic race remains static, with Hillary Rodham Clinton holding a sizable lead over Barack Obama. The New York senator, who is white, also outpaces her Illinois counterpart, who is black, among black and Hispanic Democrats, according to a combined sample of two months of polls.

A half year before voting begins, the survey shows the White House race is far more wide open on the Republican side than on the Democratic. The uneven enthusiasm about the fields also is reflected in fundraising in which Democrats outraised Republicans $80 million to $50 million from April through June, continuing a trend from the year’s first three months.

“Democrats are reasonably comfortable with the range of choices. The Democratic attitude is that three or four of these guys would be fine,” said David Redlawsk, a University of Iowa political scientist. “The Republicans don’t have that; particularly among the conservatives there’s a real split. They just don’t see candidates who reflect their interests and who they also view as viable.”

More Republicans have become apathetic about their top options over the past month.

A hefty 23 percent can’t or won’t say which candidate they would back, a jump from the 14 percent who took a pass in June.

Giuliani’s popularity continued to decline steadily as he faced a spate of headline headaches, came under increased scrutiny and saw the potential entry of Thompson in the mix; his support is at 21 percent compared with 27 percent in June and 35 percent in March.

The former New York mayor is running virtually even with Thompson, who has become a threat without even officially entering the race. The actor and former Tennessee senator has essentially stayed steady at 19 percent. McCain, the Arizona senator who is revamping his nearly broke campaign, clocked in a bit lower at 15 percent, while Romney, the former Massachusetts governor, remained at 11 percent.

None of the top candidates has a clear lead among Christian evangelicals, a critical part of the GOP base that has had considerable sway in past Republican primaries. Giuliani, a thrice-married backer of abortion rights and gay rights, had 20 percent support _ roughly even with Thompson and McCain who have one divorce each in their pasts. Romney, a Mormon who has been married for three decades, was in the single digits.

Nine Republicans and one all-but-declared hopeful, Thompson, make up the crowded GOP field. It shrunk in recent days when former Virginia Gov. Jim Gilmore, an underfunded long shot, dropped out. Such discontent with the top-tier could lead Republicans to reconsider lesser-knowns such as former Arkansas Gov. Mike Huckabee or Kansas Sen. Sam Brownback.

Among the legions of undecided Republicans is Barbara Skogman, 72, a retired legal assistant from Cedar Rapids, Iowa. She isn’t at all excited about any of the prospects. At one point, she favored McCain. At another, she was open to Giuliani. Now, she’s leaning slightly toward Romney but says she’s far from sold on him.

“I’m looking for a strong, honest person. Do you know of any?” she joked. She had an easy time detailing why she was queasy about each of the most serious contenders. “Isn’t that sad?” Then she reached a conclusion: “I just don’t know.”

Andrew E. Smith, a polling expert at the University of New Hampshire, said the number of voters in flux is no surprise, given that the primaries aren’t for another six months. “People really don’t decide who to vote for until the last couple months or days,” he said.

On the Democratic side, 13 percent declined to back a candidate, and of those who picked a candidate, some may be willing to change their minds.

Barbara Hicks, 29, an English tutor in Arlington, Va., said her friends got her to lean toward former North Carolina Sen. John Edwards but she said, “It’s not set in stone. … I don’t favor him very, very strongly.”

The only other sign that Democrats are at all agitated about their choices is the continued support for Al Gore, the former vice president and 2000 Democratic presidential nominee who says he’s not running. His popularity has slid some to 15 percent.

Otherwise, Clinton kept her strong advantage over Obama; her backers accounted for 36 percent of Democrats to his 20 percent, while support for Edwards remained essentially unchanged at 11 percent.

While neither Obama nor Edwards has threatened Clinton in national polls, both are giving her a chase in other areas. Obama leads her in fundraising for the primary and Edwards is running stronger in Iowa.

Nationally, the combined sample found Clinton has the edge among black Democrats, with 46 percent of their support to Obama’s 33 percent. Her advantage is even wider among Hispanics; she has the support of 45 percent to Obama’s 17 percent. New Mexico Gov. Bill Richardson, whose mother was Mexican, had the backing of just 5 percent of Hispanics and virtually no support among blacks.

The AP-Ipsos poll was conducted by telephone July 9-11 with 1,004 adults, including 346 Republicans and 477 Democrats. The margin of sampling error for the full sample is plus or minus 3 percentage points, plus or minus 5.5 percentage points for Republicans and 4.5 percentage points for Democrats. For the combined June and July samples, the margin of sampling error is plus or minus 3.5 percentage points for Republicans and plus or minus 3 percentage points for Democrats.

Associated Press Manager of News Surveys Trevor Tompson, AP News Survey Specialist Dennis Junius, and AP Writer Natasha Metzler contributed to this report.