The Iowa Capitol dome.

DES MOINES, Iowa — In the closest outcome in the history of the Iowa caucuses, former Massachusetts Gov. Mitt Romney edged former Sen. Rick Santorum by just eight votes Tuesday to win the first contest of the 2012 election.

With 100 percent of precincts reporting, Romney had 30,015 votes while Santorum had 30,007, according to Matt Strawn, chair of the Iowa Republican party. In terms of percentages, both Santorum and Romney claimed 24.5 percent of the vote.

The virtual dead heat in the Iowa caucuses, in which a record 122,255 Iowa Republicans participated, raises questions about whether Romney can attract support from the party’s conservative base.

On Monday, Romney reportedly crowed that he was going to win the Iowa caucuses by telling a crowd of supporters, “We’re going to win this thing.” A Romney spokesperson later downplayed the remarks and said the candidate was referring to winning the Republican nomination.

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Libertarian Rep. Ron Paul (R-Texas), who had enjoyed a lead in the polls just two weeks before the caucuses took place, finished in third place with 21.5 percent of the vote.

Troy Price, executive director of One Iowa, a statewide LGBT group, said the virtual tie demonstrates that social conservatives were unable to dominate the caucuses despite their efforts.

“This extremely close outcome shows that in spite of the millions of dollars and constant campaigning on the backs of loving, committed gay and lesbian couples in Iowa, the attempt by social conservatives to dominate the caucuses simply didn’t work,” Price said. “Rather, this tie between Rick Santorum and Mitt Romney shows the deep divisions that exist between social conservatives who want to harm loving and committed couples, and fiscal conservatives who prioritize job creation and a smaller government.”

Jimmy LaSalvia, executive director of GOProud, a gay conservative group, congratulated Romney and Paul in a statement for placing in the top three slots — but notably left out any mention of Santorum, who’s known for holding anti-gay views.

“Tonight, we congratulate Governor Romney and Congressman Paul on their strong showings in the Iowa caucuses,” LaSalvia said. “It is clear that the message of economic renewal and limited government is resonating with Republican voters.”

LaSalvia commended Romney and Paul for offering plans that he said contrasted with the “big government approach” of President Obama without resorting to anti-gay rhetoric.

“While there are certainly big differences between Governor Romney and Congressman Paul, especially when it comes to foreign policy, both chose to emphasize issues like the economy and the size of government over demonizing gay people,” LaSalvia said. “We are pleased to see that so many Republicans in Iowa are focused on the issues that unite us as conservatives, instead of the side show issues.”

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Brian Brown, president of the anti-gay National Organization for Marriage, praised both Santorum and Romney over “their photo-finish” because of the candidates’ opposition to same-sex marriage.

“It’s especially satisfying to see Senator Santorum, a longtime friend and champion for the family, come from behind to mount such a successful campaign,” Brown added.

Santorum and Romney were among the candidates that signed NOM’s pledge to oppose same-sex marriage by backing a Federal Marriage Amendment and defending the Defense of Marriage Act in court if elected president.

“The strong showing by both Santorum and Romney shows that supporting marriage is not only the right thing to do, it is the politically smart thing to do,” Brown said.

But Brown criticized Paul, who twice voted against the Federal Marriage Amendment and isn’t among the candidates who signed NOM’s pledge.

“This is a lesson that Ron Paul may be learning the hard way,” Brown said. “Paul suffered a big loss by finishing third in Iowa, a state he was expecting to win.”

Brown said ads NOM aired against the candidate in Iowa in addition to grassroots work “were a factor in Ron Paul’s poor showing.”

The results triggered the end of Rep. Michele Bachmann’s campaign. She won just 5 percent of the vote even though Iowa is her home state. Bachmann announced Wednesday she was leaving the race.

“I have decided to stand aside,” she told reporters in Des Moines on Wednesday morning.

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Former U.S. House Speaker Newt Gingrich and Texas Gov. Rick Perry, who also enjoyed the status of GOP presidential frontrunners, had less than optimal finishes. Gingrich took fourth in the caucuses with 13.2 percent of the vote and Perry came in fifth with 10.3 percent.

In a speech after the contest, Perry said he was going to scrap plans to campaign in South Carolina and return to Texas to determine whether a path to victory remains.

The strong showing for Santorum comes on the heels of comments he made that raised the eyebrows of LGBT advocates in an interview Tuesday with ABC News’ Jake Tapper.

The candidate said he opposes the 2003 U.S. Supreme Court ruling of Lawrence v. Texas, which struck down state sodomy laws throughout the country. He also said he opposes a court decision preventing states from prohibiting the sale of contraceptives.

Santorum said he personally would have voted against the state law in Texas prohibiting consensual sex between two males, but still thinks states should be able to pass such laws.

“I wouldn’t have voted for the Texas sodomy law, but that doesn’t mean the state doesn’t have the right to do that,” Santorum said. “I just didn’t think they should do it. We shouldn’t create constitutional rights when states do dumb things. We should let the people decide. If the states are doing dumb things, get rid of the legislature and replace them as opposed to creating constitutional laws that have consequences beyond the specific case that was before them.”

As Republicans in Iowa were deciding on the best candidate to represent them, Democrats also held caucuses throughout the state, even though President Obama was the only candidate on the ticket. More than 25,000 Iowa Democrats were estimated to have participated.

Obama delivered a message to supporters attending the caucuses via video and took a couple questions from attendees pledging their support to him. Among the accomplishments that he touted during the video was repeal of “Don’t Ask, Don’t Tell.”

“Because of you, we’ve been able to end the policy of ‘Don’t Ask, Don’t Tell’ so that every American who want this country that they love can have that opportunity, regardless of who they love,” Obama said.

In a statement, Sue Dvorksy, chair of the Iowa Democratic Party, said the Democratic Iowa caucus was “a great opportunity to test our campaign organization and expand our volunteer base as we move toward November.”

“In a strong show of support, more than 7,500 Iowans tonight pledged to volunteer for the campaign over the course of the next year, underscoring their commitment to continuing the change the country has seen under President Obama’s leadership,” Dvorsky said.