As they stuff millions of dollars more into campaign coffers ahead of a key fundraising deadline, 2008 White House hopefuls are plotting a campaign spending binge of unprecedented proportions.

National front-runners Democrat Hillary Clinton and Republican Rudolph Giuliani and their rivals are making a frenetic dash for cash, before the latest quarterly campaign fundraising period ends Sunday.

Soon afterwards, candidates who raised a combined 265 million dollars by mid-2007, are expected to start unleashing their wealth, hoping to damage rivals in a crucial three-month sprint to first nominating contests.

“I expect to see an advertising blitz in early voting primary states,” said Costas Panagopoulos, a political science expert at Fordham University.

Several key questions are emerging about the direction of what will likely be America’s first billion dollar election.

Can Senator Barack Obama or any other Democrat thwart the slick, nearly error-free, poll-topping Clinton campaign machine?.

Can any Republican electrify a field which has left many conservatives cold?

Obama piled up an eyepopping 58 million dollars in the first half of the year, and had 36 million left mid-year, not counting the three months fundraising to Sunday, according to reports to the Federal Election Commission.

Clinton nosed ahead in the same period with 63 million dollars raised, and had 45 million left at the end of June, according to, which tracks campaign spending.

The two rivals will go head-to-head with other Democrats in the latest party debate on Wednesday in New Hampshire.

While the money chase is close, Obama has yet to chip into Clinton’s widening lead in opinion polls.

“It doesn’t seem to me that Obama has been able to translate that fundraising prowess into support in the polls,” said Panagopoulos.

In an average of national polls by, Clinton stands at a commanding 40 percent, leading Obama on 24 percent and former senator John Edwards on 14 percent.

Clinton narrowly leads a much closer race in Iowa, expected to hold the first nominating contests with its fabled caucuses early next year, and is dominant in state polls in New Hampshire, South Carolina and Florida.

Having weathered attacks on her vote in 2002 to authorize war in Iraq and sparred with Obama on who is the best champion of change, the former First Lady can expect new attacks on what some experts see as her biggest weakness — her high negative approval ratings among some voters.

“The other candidates may start to really hit her as somebody who cannot win in a general election because of who she is,” said Professor Tom Baldino, of Wilkes University in Pennsylvania.

Among Republicans, figures which emerge after Sunday’s deadline will make interesting reading for Fred Thompson, the former senator and “Law & Order” star turned presidential candidate, who jumped into the race late, this month.

A slim take for Thompson could feed perceptions that his campaign launch was botched, and that his drive for the White House lacks energy, despite his strong showing in national and some state polls.

Giuliani, the former New York mayor running a hawkish campaign rooted in his leadership after the September 11 attacks in 2001, hopes to shore up his spot as national front-runner, despite questions about his appeal to conservatives.

One time pack leader Senator John McCain meanwhile, whose campaign almost collapsed after an ill-advised spending orgy, will also be in the spotlight.

Former Massachusetts governor Mitt Romney, strong so far in the financial stakes, has been rewarded by spending millions in Iowa and New Hampshire, with state poll leads.

An average of national Republican polls shows Giuliani ahead with 27 percent, Thompson on 22 percent, McCain on 15 percent and Romney on nine percent.

Generally, Republicans battling party discontent over the field, and saddled with the legacy of President George W. Bush’s low poll ratings, have raised less money than Democratic candidates.

In the first six months of 2007, Romney raised 44 million dollars, and burned through 32 million.

Giuliani pulled in 35 million dollars, and had 18 million left by mid-year, according to