WASHINGTON -- The oxygen is running out for Rick Santorum.

The former Pennsylvania senator has a message that appeals to the base of the Republican Party. In many ways, he is the candidate that the grassroots want. But he is in danger of falling behind Mitt Romney -- in terms of momentum and delegates -- to a degree that will be hard to make up.

Santorum's rhetorical excesses took him off track in Michigan this past week. He lost that state's primary to Romney by three points in the popular vote, costing him a huge opportunity to build on the momentum he had gained with wins in three states on Feb. 7.

And on Saturday night, Santorum lost a symbolic vote to Romney when Washington Republicans voiced their support for the former Massachusetts governor in a straw poll at caucuses around the state.

Romney was declared the winner as soon as about 50 percent of the vote had been counted. Romney won 37.6 percent, with 19,111 votes, while Rep. Ron Paul (R-Texas) narrowly edged out Santorum for second place. Paul's 12,594 votes gave him 24.8 percent of the vote, to Santorum's 12,089 votes, or 23.8 percent. Former House Speaker Newt Gingrich (R-Ga.) had 10.8 percent.

The caucus vote is nonbinding. Washington's 40 delegates will be awarded primarily based on a vote at the state Republican Party convention, which runs from May 30 to June 2.

But coming just three days before 10 states vote on Super Tuesday, it was a good headline, a momentum-booster and another step for Romney in the long march toward the nomination.

"The voters of Washington have sent a signal that they do not want a Washington insider in the White House," Romney said in a statement emailed out by his campaign. "They want a conservative businessman who understands the private sector and knows how to get the federal government out of the way so that the economy can once again grow vigorously."

New details also emerged Saturday about the extent to which Santorum's lack of campaign infrastructure will hurt him in Ohio on Tuesday. He will be ineligible for up to 18 of Ohio's 66 delegates. It had previously been reported that he could not compete for six delegates.

The Romney campaign pointed to Santorum's lack of organization in Ohio and other states to argue that he is not ready to take on President Barack Obama's reelection machine. For example, Santorum also failed to make the ballot entirely in Virginia, which will award 46 of its 49 delegates on Tuesday.

The Santorum campaign believes that despite the candidate's missteps, he is connecting with the core voters of the Republican Party in a way that Romney is not. The problem is that the GOP establishment, by and large, believes Santorum presents a far worse match-up with Obama in the fall than does Romney, even if Romney's many missteps and inability to close out the nomination have increased their anxiety about his prospects in the general election.

Romney, Santorum and Gingrich were all in Ohio on Saturday. All three participated in a televised forum on Fox News moderated by former Arkansas Gov. Mike Huckabee, who was a top contender for the GOP nomination in 2008.

The forum, filmed in a former DHL shipping plant that closed down in 2008, was highlighted by Romney's exchange with David McArthur, a small-business owner from St. Louis who told the former Massachusetts governor, through tears, that his son has not been able to receive health coverage from the Department of Veterans Affairs for a brain injury and post-traumatic stress disorder.

"To those who put their lives on the line, we owe everything they need," Romney replied, his own voice breaking at one point.

At the end of the show, Huckabee said that Romney had "showed a side of him that I had not seen: a deeply personal, emotional, passionate side that we had not really seen."

"That's been a criticism of Governor Romney. I thought he really blew the answer right out of the water. It was just a tremendous response," Huckabee added.

Santorum, meanwhile, continued to be tripped up by inflammatory comments he's made over the past few weeks. A college student, who was part of a three-person panel, asked Santorum why he had called Obama a "snob" for saying Americans should go to college and added that the comment "didn't really sit well with my campus."

As for Gingrich, he is scheduled to appear on the Sunday talk shows on ABC, CBS, NBC, Fox News and CNN. After being a nonfactor for most of the last month, he is hoping to reinsert himself back into the race by winning the Georgia primary on Super Tuesday.

But Gingrich also needs to do well in some other states where he'll be competing head to head with Santorum, like Tennessee and Oklahoma.

Santorum will break off from Ohio on Sunday to campaign in Memphis and then Oklahoma City and Broken Arrow, Okla.

Romney will go to Georgia and Tennessee before heading back to Ohio Sunday night to campaign there on Monday.

Paul, continuing his effort to pick up delegates in every nook and cranny, will visit Alaska on Sunday, going to Fairbanks and Anchorage.

The holy grail is 1,144 delegates. All the candidates are far away from that number. Romney leads the pack with 185 to Santorum's 90, Gingrich's 33 and Paul's 23.

On Tuesday, 391 delegates will be up for grabs. The Romney campaign sent out a memo from political director Rich Beeson on Saturday noting that Santorum is "already down 64 delegates," because of his failure to file a full slate of delegates in Ohio and Tennessee, as well as his total absence from the ballot in Virginia.

Beeson pushed hard to make the argument that Romney is the only candidate who has the resources to win the primary, whether it ends soon or goes for several more months. "On Wednesday, March 7, the Santorum campaign will be looking at a significant deficit to Governor Romney in bound delegates and no realistic hope of closing that gap," Beeson wrote. "The combination of proportional allocation and his regional weaknesses are going to make it virtually impossible for him catch up to Governor Romney in delegates, let alone ever get to 1,144."

Most political observers share Beeson's perspective or are at least leaning that way. That's why a very strong performance by Santorum in Ohio, as well as in Tennessee and Oklahoma, is crucial for him to keep alive his hopes of staging a huge upset in the race for the Republican nomination.

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