By Bruce Drake, CQ Staff

There’s been an avalanche of polls surveying the national presidential race, the early voting states and the big primary states that come later. For those trying to sort them out, they add up to this snapshot in time:

• Democrat Hillary Rodham Clinton and Republican Rudy Giuliani , who once appeared to be prohibitive front-runners by many measures, have tumbled badly in Iowa, New Hampshire and South Carolina, states holding key early nominating contests in January.

• Both the New York senator and former New York City mayor are holding their own much better in important big states down the road, assuming the outcomes of the early primaries don’t change the dynamics of the campaign so much that one or the other is badly wounded by the time they get there.

• In national polls, Clinton still runs strongly ahead of Illinois Sen. Barack Obama , the runner-up among Democrats, but Giuliani has been slipping precipitously back to the Republican pack.

The word “snapshot” to describe these headlines is an important one — because many of these polls, in both the early and later-voting states, show high percentages of voters who say they might change their minds before the day comes for them to vote in their states’ primaries and caucuses.

That volatility is higher among Republicans, who appear more up in the air and less satisfied about their choices. This was the top finding of a New York Times/CBS News poll taken Dec. 11. That same poll said Democrats were much happier with their choices.

In Iowa, there is the additional wild card: the importance of a voter’s second choice. That is because of caucus procedures that allow (and encourage) attendees to throw in with stronger contenders if a voter’s first choice fails to meet the delegate-qualifying threshold of 15 percent in the first round of balloting.

A Zogby poll in early December found that Clinton would win most of the support among those who make Delaware Sen. Joseph R. Biden Jr. their first choice, and she does well among those who would first choose New Mexico Gov. Bill Richardson .

Former North Carolina Sen. John Edwards , the Democrats’ 2004 vice presidential nominee, is the second choice of most who support Obama, and Obama is the second choice for those who support Clinton — though there is little chance that Clinton and Obama will fail to break 15 percent.

The tight race in Iowa is a reminder that candidates who were once way ahead of the pack, and later find themselves struggling to stay above water in the idiosyncratic currents of early state politics, often look to a “firewall” state where their organization and their support will enable them to get back on track.

That was the case in 1980, when Republican front-runner Ronald Reagan took Iowa for granted and was upset by former President George H.W. Bush. Bush tried to ride what he called his “Big Mo” — that’s momentum — into the traditional first-in-the-nation New Hampshire primary, but Reagan’s campaign regrouped and beat Bush by a landslide. Reagan rode that resurgence through the rest of the primaries, losing only four to Bush along the way.

Bill Clinton’s campaign in 1992 was in trouble, although not because of Iowa, which most Democrats skipped because home state senator Tom Harkin was on the ballot. Clinton, then the governor of Arkansas, was under siege amid stories about his military draft history during the Vietnam War and allegations of marital infidelity, but he waged an exhaustive and exhausting campaign in New Hampshire to finish second. Winning the “spin” game — by claiming that the primary victor, former Massachusetts Sen. Paul Tsongas, was a New England favorite-son candidate — Clinton claimed the title of “Comeback Kid”; rebounded to win the nomination; and unseated incumbent Bush, who had been elected in 1988 after eight years as Reagan’s vice president.

Hillary Rodham Clinton faces a similar scenario now that nearly every poll shows her in a dead heat with Obama in Iowa. Earlier, New Hampshire looked like the firewall for her campaign should she lose in Iowa. But at least two polls this week — by Rasmussen Reports and by CNN/WMUR — suggested that her firewall might be showing cracks: Both polls said the New Hampshire race is “too close to call.” Rasmussen had Clinton ahead of Obama by 3 percentage points, compared with a 10-point lead a month earlier. The poll done for CNN and New Hampshire TV station WMUR had her dropping 5 points since November, while Obama gained 8, closing the gap between them to a statistically insignificant 1 point.

On the Republican side, Mike Huckabee — the personable former Arkansas governor and one-time Baptist minister — has pulled ahead in Iowa thanks to strong support from evangelical Christians. But that appeal and dynamic doesn’t exist in New Hampshire, where he has languished in single digits. Most polls indicate Mitt Romney , the ex-governor of neighboring Massachusetts, is ahead in New Hampshire by a double-digit margin, with Giuliani and Arizona Sen. John McCain running closely together behind him.

Polls in states that vote later, as well as the national polls, suggest that Clinton, and to a much lesser extent, Giuliani can look forward to friendlier ground elsewhere if they survive the early voting.

The Quinnipiac College Institute poll of three key swing states — Florida, Ohio and Pennsylvania — show Clinton with overwhelming leads over her Democratic rivals. Giuliani remains in the GOP lead, although not by nearly Clinton’s margin, and the survey found that Huckabee is gaining in those states. Florida votes Jan. 29, Ohio on March 4 and Pennsylvania on April 22. A poll in New Jersey, which is in the mega-lineup of states voting on Feb. 5, had Clinton and Giuliani comfortably ahead, enjoying their status as residents of neighboring New York.

A SurveyUSA poll in California had Giuliani ahead of McCain by 32 percent to 18 percent, but even that was affected by the kind of slippage he has being seeing elsewhere. For the Democrats, Clinton runs 2-to-1 ahead of Obama in the nation’s most-populous and delegate-rich state.

The national polls also tell a different story than the early state polls on the Democratic side. Polls by the Associated Press, New York Times/CBS News and the Washington Post found Clinton with a still-comfortable lead over Obama.

Among Republicans, though, nearly all national polls show the commanding leads Giuliani had earlier this year have fallen off substantially. While Giuliani still leads in several, Huckabee has either vaulted into a competitive second place or is running statistically even.

Interestingly enough, a CNN/Opinion Research poll reported that in a hypothetical general election matchup, the strongest candidates are two who haven’t established themselves as front-runners in any of these states and national polls: Edwards and McCain, who is well-known nationally as a former Vietnam War hero and as President Bush’s leading competitor for the 2000 Republican presidential nomination.

The poll found that Clinton would beat Giuliani, Huckabee and Romney but lose narrowly to McCain, although McCain’s lead is within the poll’s margin of error. Obama’s results are about the same, although he is in an actual tie with McCain. But Edwards would beat all four Republicans, including McCain, by margins larger than Clinton or Obama.

As far as the issues driving the 2008 race, Gallup asked Americans to list what they will take into account in deciding their choices. Thirty-six percent of Americans say Iraq, with the economy (16 percent), health care (15 percent) and illegal immigration (10 percent) mentioned next most often. Between 3 percent and 6 percent of Americans mention homeland security or military defense, taxes, the honesty and integrity of the candidate, abortion, domestic issues, Social Security reform and international affairs, Gallup reported.