For all of Mitt Romney’s evident trouble wrapping up the Republican nomination — and sliding support against his rivals in national polls -- his favorable numbers among the party’s base have steadily improved since a bad defeat in South Carolina, according to a new Washington Post-ABC News poll.

(Click here for larger version of chart below.)

The Washington Post (Jon Cohen/The Washington Post)

Now, 69 percent of conservative Republicans express positive views of the former Massachusetts governor, a high in polls back to September and a big improvement from late January. But he has real competition for conservative support from former Pennsylvania senator Rick Santorum. Santorum — who checks in at 66 percent favorable among all conservative Republicans — tops Romney in this most basic measure of popularity among the most conservative respondents. Fully 74 percent of Republicans and independents who consider themselves to be “very conservative” have favorable views of the former senator, 12 points higher than Romney’s numbers. Santorum also has only about half the number of detractors in this key group.

Moreover, support for Santorum is more intense than it is for Romney. Among very conservative Republicans and independents, 43 percent have “strongly favorable” views of Santorum, nearly triple the number saying so of Romney (16 percent).  

Numbers for both Santorum and Romney, however, far exceed those for former House speaker Newt Gingrich, whose popularly has faded fast since he thumped the competition in the Jan. 21 South Carolina primary.

Fewer than half of Republicans — 45 percent— now express favorable views of the former speaker, down 10 percentage points from late January and 15 points from December. Gingrich now has about as many Republican detractors as he has supporters.

(Click here for larger version of chart below.)

The Washington Post (Jon Cohen/The Washington Post)

As the three — and Texas Rep. Ron Paul (not tested in this poll) — prepare to square off in a final debate before primaries in Michigan and Arizona next week, the new polls shows Santorum picking up support among GOP women.

In the new poll, 57 percent of Republican women express positive views of Santorum, up 13 points from early January, with the biggest bump in the past week. The former senator has been sharply criticized by some for speaking out against prenatal testing and women in combat and the workplace.

The one who is suffering among GOP women is Gingrich. His favorable numbers among Republican women have cratered from 65 percent in December to 52 percent in January to 37 percent now. Of the three GOP candidates in the poll, Gingrich has, by far the widest gender gap on favorable numbers (54 percent among GOP men vs. 37 percent for women).

The poll was conducted Wed. Feb. 15 to 19, among a random national sample of 1,012 adults. The margin of sampling error for the full poll is plus or minus 3.5 percentage points.

More from the Post polling team

Sign up for Post polling e-mails

Follow Post polling on Twitter

Like Post Politics on Facebook