WaPo poll: Romney 35, Gingrich 17

Yesterday’s Fox poll gave the first indication that Mitt Romney has suddenly broken through the ceiling of his polling support in 2011.  Today, the Washington Post poll corroborates that move, with a less-dramatic move upward.  In this case, it’s emphasized by the sharp decline in Newt Gingrich’s standing:

Mitt Romney holds a strong lead nationally in the race for the Republican presidential nomination, with a 2 to 1 advantage over his closest competitors, according to a new Washington Post-ABC News poll.

Romney won the first two contests in the nominating process, and none of the other candidates has been able to demonstrate the broad, sustained support among the party’s conservative base that would translate into a successful challenge. An overwhelming majority of Republicans predict that he will be President Obama’s opponent in November. …

Romney wins the support of 35 percent of all Republicans and GOP-leaners nationwide, with former House speaker Newt Gingrich (Ga.) and Rep. Ron Paul (Tex.) neck and neck with about half the support Romney enjoys. Former senator Rick Santorum (Pa.), who surged to a second-place finish in the Iowa caucuses, checks in at 13 percent, his highest level of the campaign. Texas Gov. Rick Perry runs fifth, at 9 percent, rounding out a field that shrank Monday with the decision by former Utah governor Jon Huntsman Jr. to quit the race and endorse Romney.

Unlike in the Fox poll, Romney’s support only rose five points, from 30 to 35, among the general population.  It went up six points among registered voters, and Gingrich and Paul tie at 16 in that subset.  A month ago, Gingrich scored 30 points among both, which means he’s lost about half of his support in the last few weeks.  Rick Santorum has been the main beneficiary, but some of it seems to have gone to Romney as well.

Voters in this poll still don’t have a firm grip on their decision.  Only 36% have definitely made up their mind on a candidate, with 60% saying they could change their mind yet.  Romney supporters, though, are more solid, with 43% locked into their choice and 53% saying that their vote could change.

There are a couple of curiosities in this survey, though, to keep in mind.  First, we don’t have much idea of the sample composition, and this is a series with a bad habit of skewing its sample.  The poll surveyed 1,000 adults, but we don’t know how many of them were actual Republican voters.  I’ve seen the WaPo/ABC poll sample consist of 25% or fewer Republican adults, let alone registered voters.  A sample size of 250 Republican adults, with fewer being registered voters, would not be a terribly reliable sample on which to rely for predictive modeling.  And why at this late stage of the primary is the WaPo/ABC poll still surveying the general population or registered voters?  Why not likely voters?