* Says Obama agenda about 'some phony theology'

* 'Latest low' in Republican campaign - Obama campaign says

By Samuel P. Jacobs

COLUMBUS, Ohio, Feb 18 (Reuters) - Republican presidential candidate Rick Santorum challenged President Barack Obama's Christian beliefs on Saturday, saying White House policies were motivated by a "different theology."

A devout Roman Catholic who has risen to the top of Republican polls in recent days, Santorum said the Obama administration had failed to prevent gas prices rising and was using "political science" in the debate about climate change.

Obama's agenda is "not about you. It's not about your quality of life. It's not about your jobs. It's about some phony ideal. Some phony theology. Oh, not a theology based on the Bible. A different theology," Santorum told supporters of the conservative Tea Party movement at a Columbus hotel.

When asked about the statement at a news conference later, Santorum said, "If the president says he's a Christian, he's a Christian."

But Santorum did not back down from the assertion that Obama's values run against those of Christianity.

"He is imposing his values on the Christian church. He can categorize those values anyway he wants. I'm not going to," Santorum told reporters.

A social conservative, Santorum is increasingly seen as a champion for evangelical Christians in fights with Democrats over contraception and gay marriage.

"This is just the latest low in a Republican primary campaign that has been fueled by distortions, ugliness, and searing pessimism and negativity - a stark contrast with the President who is focused everyday on creating jobs and restoring economic security for the middle class," said Obama campaign spokesman Ben LaBolt.

The campaign's response signaled a new respect for Santorum. Until this week, the Obama campaign appeared exclusively focused on Mitt Romney. Republicans are waging a state-by-state contest to pick a candidate to challenge Obama in November's election.

At a campaign appearance in Florida last month, Santorum declined to correct a voter who called Obama, a Christian, an "avowed Muslim."

Santorum told CNN after that incident, "I don't feel it's my obligation every time someone says something I don't agree with to contradict them, and the president's a big boy, he can defend himself."

QUESTIONS ROMNEY RECORD ON OLYMPICS

On Saturday, Santorum also took aim at Romney, his main Republican rival, on one of the central accomplishments of his resume, saying the former Massachusetts governor's rescue of the 2002 Salt Lake City Winter Olympics required millions of dollars in handouts from the federal government.

The attack was a response to the Romney camp trying to portray Santorum as a proponent of big government because of his use of earmarks while he served in the U.S. Senate.

"He heroically bailed out the Salt Lake City Olympic Games by heroically going to Congress and asking them for tens of millions of dollars to bail out the Salt Lake Olympic Games - in an earmark," Santorum said.

"One of his strongest supporters, John McCain called it potentially the worst boondoggle in earmark history. And now Governor Romney is suggesting, 'Oh, Rick Santorum earmarked,' as he requested almost half a billion dollars of earmarks as governor of Massachusetts to his federal congressmen and senators. Does the word hypocrisy come to mind?" Santorum said.

Romney often talks of how he turned around the struggling Olympics organization and is appearing in Utah on Saturday to mark the anniversary of the Olympics.

In a statement, the Romney campaign said Santorum was in a weak position to challenge its candidate on big spending.

"Sometimes when you shoot from the hip, you end up shooting yourself in the foot. There is a pretty wide gulf between seeking money for post-9/11 security at the Olympics and seeking earmarks for polar bear exhibits at the Pittsburgh Zoo. Mitt Romney wants to ban earmarks, Senator Santorum wants more 'Bridges to Nowhere,'" said Romney spokeswoman Andrea Saul. (Editing by Peter Cooney)