A win in the Nevada caucus has moved Mitt Romney closer to securing the Republican presidential nomination, but a new poll for the first time shows Romney losing a general election to President Barack Obama by a significant margin.

Prior polls had solidified Romney's reputation as the most electable Republican candidate, generally predicting a general election toss-up. But the latest Washington Post-ABC News poll gives Obama a 52 to 43 percent advantage among all Americans and a narrower 51 to 45 percent edge among the more partisan bloc of registered voters.

President Buoyed by January Jobs Report

The president has been buoyed by a strong jobs report that offered a glimpse of a sustained economic recovery. But the poll still found a deeply divided electorate when it comes to Obama's policies -- the percentages of Americans who said they approve of his economic or jobs-creating record were only slightly higher than those who said they strongly disapproved.

Obama appears to be winning the messaging battle. Fifty-seven percent of those who heard or read his recent State of the Union address approved of his proposals, compared to 37 percent who disapproved, while 55 percent of those who have been closely following the Republican campaign dislike what they've heard.

Although voters said they most trusted Romney to handle the economy, the budget deficit and social issues, there are signs the former Massachusetts governor's image is eroding even as he moves to consolidate his frontrunner status. Fifty-two percent of Americans said they liked Romney less the more they heard about him, compared to just 24 percent who said they liked him more.