Rick Santorum
Operation Hilarity encourages Democrats in open primary states to cast a vote for Rick Santorum, a candidate that some say has no real chance of winning an election against President Obama. REUTERS

(Reuters) - Rick Santorum has surged into a virtual tie with Mitt Romney in a national poll on Monday, becoming the clear favorite of Tea Party voters and white evangelicals.

Thirty percent of Republican and Republican-leaning voters favored Santorum, while 28 percent preferred Romney, the Pew Research Center poll said.

Almost twice as many Tea Party supporters and white evangelical Christians chose the former U.S. senator for Pennsylvania compared with the former Massachusetts governor.

The Tea Party movement represents a loose-knit coalition of fiscally conservative activists who helped Republicans take back the House of Representatives in the 2010 elections.

Santorum swept Republican nominating contests in Missouri, Minnesota, and Colorado last week -- his first victories since being announced the winner of the Iowa caucuses in January -- and has since closed a wide lead Romney held over him.

In a Pew poll in January, Romney was ahead of Santorum with 31 percent to 14 percent.

Data for Monday's poll was based on telephone interviews from Feb. 8 through Sunday of 552 registered Republican and Republican-leaning voters. The margin of error was plus or minus 5 percentage points.

Another poll over the weekend found Santorum leading Romney by 15 points, at 38 percent compared to Romney's 23 percent.

Santorum, once considered an underdog in the race, is known for his staunchly conservative and sometimes polemical statements on abortion and gay marriage. The two men are headed for a showdown at the primary in Michigan on February 28.

(Reporting By Lily Kuo)