It’s getting fairly boring to talk about the raw national numbers in the race for the Democratic Presidential nomination. Each set of weekly data shows the same general story line. As a commentary by Douglas Schoen observed last week, the story line is that Hillary Clinton has clearly strengthened her position as frontrunner during the first eight months of 2007.

Last week, Rasmussen Reports noted that dislodging Clinton from the top spot will require something to happen that makes Iowa a four-letter word in the Clinton household.

But, it’s a long time until real voters get involved in the delegate selection process during the Iowa caucus. That gives Obama and Edwards hope.

Today, the frontrunner is unveiling a health care proposal. This is a huge issue among Democrats and has the potential to remind voters of the Senator’s botched attempt at health care reform in the early days of her husband’s Administration. However, the fact that Clinton is addressing the issue head on at this point probably indicates that this will not be the issue for Obama and Edwards to move on. To date, Clinton has run a very disciplined campaign and it must be assumed that this health care proposal will be designed to address concerns about how the issue was handled by the then First Lady fifteen years ago.

In the end, the situation in Iraq is probably the biggest single threat to Clinton’s nomination. That’s partly because the issue generates so much passion among segments of the Democratic base, but primarily because events could shift in a way to force uncomfortable tactical choices on the candidates. Some of the choices that might help in the Democratic Primary might hurt later in the general election.

Another factor is that women are far more supportive of Clinton than men. Women are also more committed to quickly bringing home troops from Iraq than men. So, it is possible to envision a scenario where the issue of Iraq rattles the Democratic base and shakes up the Democratic race. If that happens, Edwards or Obama may be able to defeat Clinton in the Iowa caucus and gain a platform upon which to press a further campaign.

Defeating Clinton in Iowa will not be enough for either of those candidates, but it is an essential first step.

But, the key fact remains that something significiant will have to change for someone other than Clinton to win the Democratic nomination at this point.

Rasmussen Reports conducts national telephone surveys on the Presidential race every night and releases updated data from our Presidential Tracking Poll by noon each day, Monday through Friday.

For the seven days ending September 16, 2007, Hillary Clinton earns 40% of the vote. Barack Obama is second at 21% followed by John Edwards at 15%. New Mexico Governor Bill Richardson tops the second-tier candidates at 5% followed by Ohio Congressman Dennis Kucinich (3%) and Delaware Senator Joe Biden (2%) and Connecticut Senator Chris Dodd (1%). Former Alaska Senator Mike Gravel registers less than 1% support. Thirteen percent (13%) of Likely Democratic Primary Voters are undecided. (review history of weekly results).

The seven day results typically include interviews with more than 1,000 Likely Democratic Primary Voters. This includes both Democrats and those independents likely to vote in a Democratic Primary. In some state primaries, independent voters are allowed to participate in party primaries while in others they are excluded. The margin of sampling error for the weekly update is +/- 3 percentage points with a 95% level of confidence.

Updates prior to July 16 were based upon four days of polling conducted the Monday through Thursday preceding release.

Rasmussen Reports continuously updates general election match-ups and other measures for all Republican and Democratic Presidential candidates.