Mitt Romney's overall favorable ratings have dropped, while Rick Santorum's standing has jumped among Republicans, according to a new national survey.

A CNN/ORC International poll released Tuesday indicates Romney's popularity has especially taken a tumble among Republicans, with a 13-point decline in positive reviews from his own party.

In the new survey, 54 percent of Republicans said they hold a favorable opinion of Romney, while 67 percent said the same in January. Among all Americans, 34 percent described the candidate as likable, down from 41 percent last month.

Meanwhile, Santorum's recent victories have boosted his standing among Republicans, 56 percent of whom had a good opinion of the former Pennsylvania senator, up from 49 percent in January.

The survey was conducted Friday through Monday, the tail end of a big week for Santorum with three contest victories followed by a spike in fundraising and poll numbers.

But among all Americans, Santorum's favorable rating has remained flat. Thirty-two percent held a good opinion in the new survey, while 31 percent said the same in January.

Texas Rep. Ron Paul and former House Speaker Newt Gingrich received positive reviews from roughly half of all Republicans.

But those numbers declined when Americans of all political affiliations were surveyed. In that case, Paul came in at 42 percent, ahead of Romney and Santorum, and Gingrich's favorable rating fell to 25 percent.

That leaves only one presidential candidate in the race with a national favorable rating above the 50 percent mark: President Barack Obama.

Among all Americans, Obama received positive reviews from 53 percent, with the poll suggesting he may have grown more popular in recent months.

Asked about issues, Republicans see Romney as the candidate most suited to handle the economy, taxes, health care and the deficit.

Gingrich, meanwhile, has a major advantage on foreign policy and illegal immigration, and Santorum is viewed as most equipped on abortion issues.

The CNN poll was conducted by ORC International from February 10-13, with 1,026 adult Americans questioned by telephone. The survey's overall sampling error is plus or minus three percentage points.

The sample also includes 937 interviews among registered voters, with a sampling error of plus or minus three percentage points.