By Stephanie Condon | CBS | Nov 15, 2011

The Iowa caucuses are just seven weeks away, but Republican voters in the nation's first presidential nominating state seem as torn as ever over the GOP field.

A new Bloomberg poll of likely caucus participants shows a four-way tie in Iowa, with Rep. Ron Paul joining Mitt Romney, Newt Gingrich and Herman Cain in the top tier of candidates. Underscoring the uncertainty in the race, 60 percent of respondents said they could be persuaded to back someone other than their first choice for the nomination.

The poll, conducted November 10 - 12 by the West Des Moines-based firm Selzer & Co, shows Cain in the lead with 20 percent, while Paul comes in at 19 percent. Romney wins 18 percent support, and Gingrich earns 17 percent. The margin of error is 4.4 percent.

While Christian conservatives have more influence in Iowa than they do in the rest of the nation, only a quarter of likely caucus-goers say social issues are more important this year than economic issues. As many as 71 percent say they're voting on issues like jobs and taxes.

The focus on economic issues has likely advantaged Paul, who is known for his strong libertarian views. The Texas congressman wins the most support, 32 percent, from likely caucus-goers who say they've made up their minds. Romney wins 25 percent of those who are decided, followed by Gingrich at 17 percent. On top of that, 69 percent of Iowa voters who supported Paul in 2008 are once again supporting him.

Just 41 percent of Romney's support comes from Iowa voters who supported him in the 2008 caucuses. More than half, 58 percent, of likely caucus-goers said support for a health insurance mandate (which Romney passed in Massachusetts as governor and which President Obama passed at the federal level) would "rule out" their support for that candidate.

Cain's standing hasn't dipped dramatically since revelations of sexual harassment charges against him from the 1990's came out. Still, 37 percent of Iowans are waiting for more information before deciding whether they believe Cain's denials.