U.S. Republican presidential hopeful Rick Santorum, fresh from surprise wins in three nominating contests, is enjoying a new boost to his campaign with polls showing his support is surging.

Three major opinion surveys indicate Santorum is in a virtual tie with former Massachusetts governor Mitt Romney.

A CBS News / New York Times poll shows Santorum with 30 percent support among Republican primary voters, compared to 27 percent for Romney. The lead is within the margin of error. The latest figure is a major shift for Santorum, who received just 16 percent support in a similar poll in January.

A Pew Research survey indicates Santorum, a former Pennsylvania senator, has 30 percent support, compared to Romney's 28 percent. President Barack Obama, a Democrat, leads the candidates in a general election match-up.

A Gallup poll indicates 32 percent of registered Republican voters back Romney, slightly edging out Santorum's 30 percent. Former House speaker Newt Gingrich, who had led the field as recently as last month, is in third with 16 percent, and Texas Representative Ron Paul is fourth at 8 percent.

Last week, Santorum pulled off unexpected wins in nominating contests in the states of Missouri, Minnesota, and Colorado. But later in the week, Romney was triumphant in the caucuses Saturday in the northeastern state of Maine.