PPP has done some early polling. Tom Jensen's summary:
In the critical early state of New Hampshire Romney continues to hold a dominant polling advantage, with 40% to 13% for Huckabee and 10% each for Newt Gingrich and Sarah Palin. If Tim Pawlenty, Mike Pence, Mitch Daniels, or John Thune somehow emerges as the winner in New Hampshire they'll be able to truthfully say they started out with nothing- they poll at 4%, 3%, 1%, and 1% respectively.
If Romney really does run he puts the New Hampshire primary at some risk of being irrelevant. If he continues to post huge leads in the polls there other top contenders could end up just writing it off and focusing their efforts on states like Nevada, South Carolina, and Florida that could have more competitive contests.
Weigel analyzes the poll and calls Romney's support "wide but not deep." Some general election polling:
In Pennsylvania 11% of 2008 Obama voters say they're inclined to vote Republican next time while only 2% who voted for McCain say they would now vote for Obama. Similarly in New Hampshire 11% of Obama voters are leaning toward supporting a GOP candidate next time to just 4% of McCain voters he's converted to his side. And in Colorado it's 12% who supported Obama the first time around who are now looking more toward the Republicans and only 5% of McCain voters who say Obama's won them over.
Based on last week's results the state out of this group that might be most worrisome for Obama is New Hampshire, where his numbers have fallen precipitously and the Republican Senate candidate won by greater than 20 points.