WASHINGTON -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.