ABC News' Amy Walter, Jake Tapper Shushannah Walshe and Michael Falcone report:

DES MOINES - Though Rick Santorum ultimately came up short in Iowa to Mitt Romney by the slimmest of margins, he won the battle of expectations. More important, he's leaving his top rivals for the title of conservative alternative to Mitt Romney - Rick Perry and Newt Gingrich - in the dust.

So what does Santorum do now?

He needs to solidify his status as the anti-Romney, consensus conservative. The best way to do this is to show that he can consolidate that base in states other than Iowa.

But New Hampshire isn't a natural fit for Santorum. In Iowa, 58 percent of Republican caucus-goers defined themselves as evangelicals. In New Hampshire, meanwhile, just 23 percent of 2008 Republican primary voters characterized themselves as such. In Iowa on Tuesday night, 14 percent of these voters said that abortion was their top concern, and almost 60 percent of those supported vehemently anti-abortion rights Santorum. Over half of Republican primary voters in New Hampshire said they thought abortion should be legal.

So, why not go straight to South Carolina?

Sources close to the campaign say that Tuesday night's strong showing in Iowa coupled with another one in New Hampshire could solidify the race as a Romney vs. Santorum contest. And more specifically, a battle between a candidate they will try to cast as a moderate (Romney) vs. the "true" conservative (Santorum). It was also evident from Santorum's victory speech on Tuesday night that he is intent on framing the race as a contrast between his own blue collar roots and Romney's far more privileged upbringing.

Santorum' advisers argue that despite Romney's lead in the polls in New Hampshire, they too have laid the groundwork to be competitive there. They add that although the former Pennsylvania senator has basically lived in Iowa for the past few months, he has managed to log almost as many days in New Hampshire as Romney.

"I'm not saying that we're going to win New Hampshire," Santorum adviser Hogan Gidley said in an interview with ABC News, "but we're going to New Hampshire and we're going to fight."

Gidley said the campaign's goal over the coming weeks would be to prove that Santorum can go "toe to toe with Mitt Romney in any part of the country."

What's more, Santorum doesn't need to win New Hampshire, he just needs to do better than any other candidate not named Romney. If he does that, he can effectively claim the mantle of the conservative alternative. To that end, Santorum will travel directly to New Hampshire on Wednesday and remain there at least until Sunday when, as of now, he plans to travel to South Carolina for a day of campaigning before returning to New Hampshire.

With his newfound place near the top of the Republican presidential field, Santorum will also be under the microscope in a way that he never has before. He has yet to have a real media scrubbing. Even if his opponents don't have the cash to compete, the four debates taking place between now and the Jan. 21 South Carolina primary give his rivals a national television platform to make their case.

But, with Perry "reassessing" his campaign in Austin and Gingrich praising Santorum while bashing Romney and Paul, Santorum may not have to endure the debate pile-on this Saturday that other insurgent candidates have been subject to during previous outings.

To bolster their ground operation in the critical early nominating states ahead, campaign manager Mike Biundo said that the campaign would be hiring more staff, but would not spend millions of dollars like other campaigns. Rather they will rely on the grassroots support they already have and are continuing to build.

"Our organization is lean and it's mean," Gidley added. "We will never be the bloated, behemoth, bureaucratic machine that some of these campaigns are."

The campaign also said they are running positive television ads in New Hampshire and South Carolina and that traditional fundraising has tripled in last week and shot up 500 percent online.

On Tuesday night, Gidley attributed the campaign's success in Iowa to a simple formula: "We offered a clear conservative alternative to a moderate like Mitt Romney."