According to a new poll, fewer than six in 10 Republicans and GOP-leaning independents see former Alaska Gov. Sarah Palin, shown here in December, in a favorable light. (Virginia Postic/AP)

Sarah Palin’s ratings within the Republican Party are slumping, according to a new Washington Post-ABC News poll, a potentially troubling sign for the former Alaska governor as she weighs whether to enter the 2012 presidential race.

For the first time in Post-ABC News polling, fewer than six in 10 Republicans and GOP-leaning independents see Palin in a favorable light, down from a stratospheric 88 percent in the days after the 2008 Republican National Convention and 70 percent as recently as October.

In one sense, the poll still finds Palin near the top of a list of eight potential contenders for the GOP nomination. The former vice presidential candidate scores a 58 percent favorable rating, close to the 61 percent for former Arkansas governor Mike Huckabee and 60 percent for former Massachusetts governor Mitt Romney, and better than the 55 percent that onetime House speaker Newt Gingrich (Ga.) received.

But Palin’s unfavorable numbers are significantly higher than they are for any of these possible competitors. Fully 37 percent of all Republicans and GOP-leaning independents now hold a negative view of her, a new high.

In another first, fewer than 50 percent of Republican-leaning independents — 47 percent — hold favorable views of Palin.

She has given almost no indication of how seriously she is considering a 2012 bid.

Some have suggested that Palin and Huckabee, both of whom work for Fox News Channel, might need to decide before a May 5 presidential debate in South Carolina, which is being sponsored by the network.

It has long been clear that Palin is a polarizing figure amid the overall electorate — she typically receives negative reviews from Democrats — but this poll indicates that she may have a similar effect among some of the voters she would need to win the nomination.

Overall, 17 percent in this sample have “strongly unfavorable” opinions of her (among GOP-leaning independents, the number rises to 28 percent). At the same time, the percentage of Republicans and leaners with “strongly favorable” views is at a new low, 26 percent.

In contrast to Palin’s dip, Romney has solidified his standing in this group.

At the beginning of voting in the 2008 primaries, 36 percent of Republicans and GOP-leaning independents held unfavorable views of him; now that number has dipped to 21 percent. Three years ago, as many held strongly unfavorable as strongly favorable views of Romney. In the new poll, he has a 3-to-1 advantage on intensity.

Others frequently mentioned as possible candidates remain largely unknown to broad swaths of the Republican electorate.

Large numbers of those polled offered no opinion about Mississippi Gov. Haley Barbour (57 percent no opinion), former Minnesota governor Tim Pawlenty (58 percent), Indiana Gov. Mitch Daniels (66 percent) and former Utah governor Jon Huntsman Jr. (68 percent), who is wrapping up his service as the Obama administration’s ambassador to China.

This telephone poll was conducted March 10 to 13, and included interviews with 414 self-identified Republicans and GOP-leaners. The margin of sampling error is five percentage points.

Polling manager Peyton M. Craighill contributed to this report.