Huckabee, Rubio and Paul perform best in head-to-head match-ups with Clinton.
Clinton leads Walker 52 percent to 40 percent in a hypothetical 2016 matchup in Wisconsin.
A new poll finds Clinton winning every head-to-head GOP match-up by double digits.
Eighty-six percent of Democrats could support her for president, according to new poll.
Walker gets 18 percent compared to 16 percent for Bush.
A new Quinnipiac poll suggests Hillary Clinton could be beatable in Virginia and Colorado.
The percentage of likely caucus-goers who viewed Romney unfavorably rose by 10 points.
The economy had been voters' chief worry for the last six years, Gallup says.
A strong majority said they were contacted by campaigns too many times and saw too many ads.
The campaign post-mortem is "an admonishment to Democrats," a pollster says.