Donald Lambro

"I think the question is, as Clinton continues to grow her support, has she already topped off? Has she already reached her maximum level of support in the Democratic primaries?" said Bud Jackson, a Democratic media consultant. Jackson, who produced a TV video touting Sen. Barack Obama's possible candidacy for the "Draft Obama" committee, said that, although Obama "is far less known than Hillary, he still has room to grow his support.

"All these candidates who are not Hillary, if some of them drop out, as they will, many Democrats conclude their support will go to someone other than Hillary," he said.

The national polls all show Clinton with a significant lead (39 percent in the Washington Post poll) over a large field of challengers, with Obama in second place at 17 percent, former North Carolina Sen. John Edwards at 12 percent and Al Gore at 10 percent.

But many Democrats dismiss her lead at this point as "mostly name recognition" and they point to what happened to then-frontrunner Dean when his '04 candidacy imploded in Iowa.

"Any Democrat who perceives themselves as the frontrunner is vulnerable because in a primary anything can happen and oftentimes does," said Ohio Democratic chairman Chris Redfern.

The early lineup in Iowa gives us an advance peek at what can happen to Clinton's frontrunner status when Democrats prepare to caucus a year from now. Edwards leads the pack, followed by Iowa Gov. Tom Vilsack, Obama and Clinton, Tully told me.

Edwards, who sees Iowa as Clinton's undoing, has been building his campaign organization there ever since he came in second to Sen. John Kerry in 2004. A win in Iowa would give him momentum going into the Nevada caucuses on Jan. 19, where he has strong labor backing, and in New Hampshire three days later. But if Obama gets into the race, "it's going to make it more difficult for Hillary because, to be successful, she needs a large percentage of the African-American vote and I'm not sure that would happen with Barack in the race," Tully said.

You can't count Clinton out, of course, but the word among Democrats here is she has a lot of obstacles to overcome before she can become her party's nominee.

Donald Lambro

Donald Lambro is chief political correspondent for The Washington Times.