MANCHESTER, NH -- Rick Santorum finished in fifth place Tuesday in the New Hampshire primary election, earning only 9.3% of the vote. The showing was a significant drop-off in momentum after essentially tying Mitt Romney in the Iowa Caucus last week.

"We knew it would be tough...we built this campaign here in New Hampshire in just a short period of time," Santorum told a small group of supporters after most of the election results had been reported.

Although Santorum didn't expect to do well in New Hampshire -- a state where Romney was predicted to win by a large margin and where a strong libertarian composition meant a robust turnout for Ron Paul -- finishing below 10% must have been a disappointment.

On Tuesday morning, Santorum was already feeling pessimistic about the primary; he told a group of reporters that he'd "be content" with a double-digit finish. But, as ABC News White House Correspondent Jake Tapper tweeted last night, Santorum has made more campaign trips to New Hampshire than any other candidate, aside from Jon Huntsman who did heavy campaigning there while ignoring the state of Iowa.

Unlike some of his rivals, Santorum didn't spend any money on advertising in New Hampshire. Instead, his campaign plans to use what's left of its remaining cash reserves in South Carolina. At The Derryfield restaurant, Mike Biundo, Santorum's campaign manager, said they planned to spend $1 million on advertising in South Carolina, a state where Santorum is expected to have a much stronger showing.

Santorum has sought to persuade the nation that Iowa won't be the climax of his campaign. After being compared to Mike Huckabee, the social conservative who won the Iowa Caucus in 2008, Santorum claimed that being from near New Hampshire gave him an advantage that Huckabee never had. Clearly, it wasn't enough: Santorum finished lower in New Hampshire than Huckabee did.

While Santorum is expected to do better in South Carolina on Jan. 21, David Catanese at Politico points out that the former Pennsylvania congressman hasn't set foot there since early November.

Video by HuffPost's Hunter Stuart