DES MOINES, Iowa (AP) -- Mitt Romney was locked in a dead heat with Rick Santorum in Iowa’s Republican presidential caucuses, the opening contest in the campaign to pick a challenger to President Barack Obama.

Romney, the longtime front-runner, and Santorum, whose campaign only recently gained momentum, each had about 25 percent of the vote with 99 percent of the state’s 1,774 precincts reporting.

Texas congressman Ron Paul was running a close third in the caucuses -- evening meetings held at 809 locations across the midwestern state Tuesday.

The results were a respectable showing for Romney, even if the final tally doesn’t put him on top. Iowa, with its core of evangelical voters, was not considered a natural stronghold for the former governor of the liberal state of Massachusetts. He clearly remains the candidate to beat for the party’s nomination going into next Tuesday’s New Hampshire primary, where he is the clear favorite.

Still, Iowa also reflects Romney’s inability to build support beyond the 25 percent level he has held for months in national polls -- even though he is generally considered the most formidable challenger to Obama in the seven-candidate field.

But the results also show no obvious alternative to Romney. Despite their strong performances Tuesday, Santorum and Paul remain longshots.

Santorum, a former Pennsylvania senator who for months languished at the bottom of Republican polls, may be hard-pressed to repeat his Iowa performance, where his solid conservative stances on social issues like abortion and gay marriage resonated with Republican voters. It’s not clear whether the message will work as well in states where the economy is a bigger issue or if he can come up with the funds or organization to sustain a national campaign.

Also, he has yet to face the intense scrutiny that has caused other conservative challengers to Romney to wither as soon as they climbed to the top of polls.

Paul’s advocacy of small-government, libertarian values has won him a devoted core of supporters, including in the important tea party movement which fueled the Republican wave victory in the 2010 congressional elections. But his anti-interventionist foreign policy and criticism of aid to Israel puts him at odds with much of the party.

The two rivals many Republicans saw as having the best backgrounds to challenge Romney -- former House Speaker Newt Gingrich and Texas Gov. Rick Perry -- were far behind the pack in fourth and fifth places, respectively. Minnesota congresswoman Michele Bachmann finished a distant sixth. The seventh candidate, former Utah Gov. Jon Huntsman, did not campaign in Iowa.

Perry said he was heading to Texas to decide whether to continue his campaign. Bachmann‘s campaign manager, Keith Nahigian, suggested she might drop out, but she signaled otherwise when she spoke to supporters a short while later. Both Perry and Bachmann had been in the top tier of candidates earlier in the race.

It’s not clear as the Republican field narrows whether the party will rally behind Romney as the inevitable nominee or coalesce behind an anti-Romney alternative such as Santorum.

Returns from 1,749 of 1,774 precincts showed both Romney and Santorum with 24.6 percent and Paul with 21.5. Romney had 29,683 votes, Santorum had 29,673 and Paul 25,976.

Gingrich had 13 percent, followed by Perry, 10 percent, and Bachmann with 5 percent.

No matter how close the final results in Iowa, state Republican Party officials said there were no plans for a recount.

Iowa has an uneven record when it comes to predicting national winners. It sent Obama on his way in 2008, but eventual Republican nominee John McCain finished a distant fourth here to former Arkansas Gov. Mike Huckabee. The 100,000 or so voters in the Republican caucuses are disproportionately white and more conservative than the overall American electorate.

Unlike in a primary, in which voting occurs over hours, the Iowa caucuses were meetings held in schools, churches and other locations where Republicans gathered for an evening of politics. Each presidential candidate was entitled to have a supporter deliver a speech on his or her behalf before straw ballots were taken.

Under party rules, caucus results have no control over the allocation of Iowa’s 25 delegates to the Republican National Convention in August, when the nominee is formally selected. The Associated Press uses the caucus outcome to calculate the number each candidate would win if his support remained unchanged in the pre-convention months.

Romney, who finished second in Iowa in 2008 despite a costly effort, initially campaigned cautiously this time around. But that changed in the race’s final days as he pursued a first-place finish, running as a conservative businessman with the skills to fix the economy.

His rivals argued that Romney wasn’t nearly conservative enough on the economy and social issues such as abortion and gay rights.

Democrats watched carefully in a state that has swung between the two parties in recent presidential elections.

Obama was unopposed for his party’s nomination. Even so, his re-election campaign set up eight offices across Iowa, made hundreds of thousands of calls to voters and arranged a video conference for the president with caucus night supporters.

“This time out is going to be in some ways more important than the first time,” Obama told Democrats across the state. “Change is never easy.”

The state‘s leadoff spot has been a fixture for decades. Democrats moved the caucuses up to early January in 1972, and Republicans followed suit four years later.