WASHINGTON (Reuters) - Democratic front-runner Hillary Clinton trails five top Republican presidential contenders in general election match-ups, a drop in support from this summer, according to a poll released on Monday.

Democratic presidential candidate Senator Hillary Clinton (D-NY) speaks to supporters during a campaign rally in Perry, Iowa November 25, 2007. REUTERS/Carlos Barria

Clinton’s top Democratic rivals, Barack Obama and John Edwards, still lead Republicans in hypothetical match-ups ahead of the November 4, 2008, presidential election, the survey by Zogby Interactive showed.

Clinton, a New York senator who has been at the top of the Democratic pack in national polls in the 2008 race, trails Republican candidates Rudy Giuliani, Mitt Romney, Fred Thompson, John McCain and Mike Huckabee by three to five percentage points in the direct matches.

In July, Clinton narrowly led McCain, an Arizona senator, and held a five-point lead over former New York Mayor Giuliani, a six-point lead over former Tennessee Sen. Thompson and a 10-point lead over former Massachusetts Gov. Romney.

She was not matched against the fast-rising Huckabee, a former Arkansas governor, in the July poll.

The results come as other national polls show the race for the Democratic nomination tightening five weeks before the first contest in Iowa, which kicks off the state-by-state nomination battles in each party.

Some Democrats have expressed concerns about the former first lady’s electability in a race against Republicans. The survey showed Clinton not performing as well as Obama and Edwards among independents and younger voters, pollster John Zogby said.

“The questions about her electability have always been there, but as we get close this suggests that is a problem,” Zogby said.

Obama, an Illinois senator, and Edwards, a former North Carolina senator, both hold narrow leads over the Republican contenders in the hypothetical 2008 match-ups.

“It all points to a very competitive general election at a time when many people think the Democrats are going to win the White House,” Zogby said.

The poll of 9,355 people had a margin of error of plus or minus one percentage point. The interactive poll surveys individuals who have registered to take part in online polls.

(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)