Riding the strong momentum out of a trio of victories in the U.S. Republican presidential nomination contests a week ago, Rick Santorum has edged out long- time front-runner Mitt Romney to the top of the field, according to new national polls released on Tuesday.

Thirty-four percent of Republicans and independents who lean towards the GOP say they back Santorum, the former senator from Pennsylvania, as the party's presidential nominee, with 32 percent backing Romney, the former Massachusetts governor, according to a CNN/ORC International survey.

Texas congressman Ron Paul came in third at 16 percent, with former House Speaker Newt Gingrich at 15 percent.

This was the latest national poll that indicated Santorum's lead in the race. He leads Romney by 30 to 27 percent in a new national poll by CBS News and the New York Times released Tuesday. Paul took the third place with 12 percent, and Gingrich came in last at 10 percent.

A Pew Research poll released on Monday found Santorum with 30 percent support of Republicans nationally, two points ahead of Romney. Gingrich and Paul got 17 percent and 12 percent of the vote respectively.

Santorum's recent surge was attributed to his sweeping victories in caucuses in Colorado and Minnesota and a non-binding primary in Missouri last Tuesday, making the former senator a more competitive conservative challenger to Romney than the former speaker.

The CNN poll showed that Santorum has a sizable edge over Romney among conservative voters. By a margin of 45 to 29 percent, he leads Romney among self-described tea party movement supporters.