Romney's Santorum Problem: No Easy Targets

* Hard for Romney to best Santorum on social policy issues

* New poll shows fresh momentum for former Pa. senator

* Romney attacks on 'earmarks' could be too arcane for many voters

By Ros Krasny

PORTLAND, Maine, Feb 12 (Reuters) - U.S. Republican presidential hopeful Mitt Romney has a Rick Santorum problem that can't be easily swept aside, even with wins in the sparsely attended Maine caucuses and a poll of conservative activists.

The former Massachusetts governor arguably has fewer effective weapons against Santorum than he was able to pull out against Newt Gingrich after getting a thumping in South Carolina from the former speaker of the U.S. House of Representatives.

As they battled for the 2012 Republican nomination, Romney attacked Gingrich on several fronts, scoring a big hit with ads focused on Gingrich's ethics violations in Congress.

The attacks helped carry Romney to front-runner status in the race to face Democratic President Barack Obama in November - until Santorum roared back into the winner's circle with three victories last week in Colorado, Minnesota and Missouri.

But his criticism of the former U.S. senator from Pennsylvania has been confined to subjects like his support for spending bills and local spending projects known as earmarks.

It would be difficult for Romney to find a foothold in using social issues against Santorum, a Catholic veteran of the American culture wars who has prayed on the floor of the U.S. Senate and whose campaign events are often dubbed part of a "Faith, Family and Freedom" tour.

Santorum and Gingrich have been vying for the "true conservative" mantle to lure more conservative Republican primary voters who mistrust Romney as too moderate.

By contrast, Romney has essentially staked his White House big on one selling point: jobs.

Recently, Romney, along with his rivals, has sharpened his rhetoric in the controversy that is pitting Catholic bishops against the Obama administration over birth control.

The former venture capitalist made a mini-comeback on Saturday with a 39 percent victory in Maine's caucuses, beating U.S. Rep. Ron Paul of Texas by a few hundred votes in a poorly attended contest. Romney also won the Conservative Political Action Conference straw poll that day.

Santorum brushed off the straw poll victory, accusing Romney on CNN of "buying" his 7-point win. The New York Times reported that the Romney campaign bussed in students from local colleges, an evergreen tactic at straw polls from Iowa to Washington.

Santorum also embraced his third-place finish in Maine. "We ended up with 18 percent, really having not appeared up there or done anything," he said on ABC's "This Week."

"BEATING THE TAR OUT OF HIS OPPONENTS"

Romney has the money to fund a campaign of negative ads against Santorum similar to the hardball policy used against Gingrich in Florida's primary last month.

The Romney campaign and "Restore Our Future," the Super PAC supporting him, spent an estimated $15 million on TV ads in Florida to tear down Gingrich after his South Carolina win.

"He's been able to win in these early primary states by, you know, beating the tar out of his opponents by four- and five-to-one on television," Santorum said on ABC.

The next test will come at the Feb. 28 primary in Michigan where Romney's father was a three-term governor.

Romney's attacks have been centered on Santorum's Senate legislative record, including support for spending earmarks and votes to raise the debt ceiling. That tactic may not be a dealbreaker for some of the conservatives Christians and others now flocking to Santorum's campaign.

A national poll on Saturday by Public Policy Polling showed Santorum at 38 percent to Romney's 23 percent, 17 percent for Gingrich, and 13 percent for Paul.

"Part of the reason for Santorum's surge is his own high level of popularity," the group said. "But the other, and maybe more important, reason is that Republicans are significantly souring on both Romney and Gingrich."

Romney's favorability was barely above water at 44 percent to 43 percent, a 23-point net decline from December, suggesting his response to releasing his tax returns, negative campaigning and other missteps are hurting his image.

The polling institute said Santorum was "completely dominating" the most right-leaning Republicans.

The former senator faced questions on ABC on Sunday about his book "It Takes a Family" where he seemed to suggest women were pressurized by radical feminists to work outside the home.

Years before the current Catholic birth control controversy, Santorum said that contraceptives harm women and society. He has also enraged the gay community, as recently as January, by equating same-sex marriage with polygamy.

Santorum's conservative credentials may land him in trouble in a larger, more diverse electorate, but for the voters who typically turn out for Republican primaries, he seems to be hitting a sweet spot.

Susan Wiswell, 56, of Kittery, a nurse who said social issues should be more prominent in the national discourse, voted for Santorum in the Maine caucus.

"He's a consistent conservative both on fiscal and social issues as well. He's very clean-cut. It would be hard for Obama to smear him. He's just a very solid, modest individual that I could trust," Wiswell said. (Editing by Doina Chiacu)