Ron Paul moves to top tier.

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.Link