Iowa caucuses win split between Romney and Santorum
Iowa's Republican caucuses have been certified as a split decision between Rick Santorum and Mitt Romney because of missing data.
Former Massachusetts Governor Romney was declared the winner of the 3 January presidential nominating contest by eight votes.
But a new count by state officials puts Mr Santorum ahead by 34 votes.
However, results are missing from eight precincts. The Romney campaign said in a statement it was a "virtual tie".
The news was first reported by the Des Moines Register.
Mr Romney is the front-runner in the state-by-state race for the Republican Party's nomination to challenge Democratic President Barack Obama for the White House this November.
Iowa Republican Party chairman Matt Strawn announced the new results at a news conference on Thursday morning.
According to the certified vote totals, Mr Santorum won 29,839 votes while Mr Romney had 29,805 - a difference of 34 ballots.
Texas Congressman Ron Paul finished third with 26,036.
But the state Republican Party has not named an official winner because of the vote-count muddle.
Results from eight of the state's 1,774 precincts are missing.
"Just as I did on the early morning hours on January 4, I congratulate Sen Santorum and Gov Romney on a hard-fought effort during the closest contest in caucus history,'' Mr Strawn said.
Doubt was first cast on the result soon after Mr Romney was declared the winner, when a vote-counter in one precinct said the published figures differed from what he observed.
At the time, state Republican officials played down any suggestion of inaccuracies.
Mr Romney went on to enjoy a solid win in New Hampshire, where the second presidential nominating contest was held. Mr Santorum came fifth in that contest.
Santorum campaign spokesman Hogan Gidley told CNN on Thursday: "The narrative for a long time has been that Mitt Romney was 2-0.
"If these results are true and Rick is ahead by 34 votes, then that's not the narrative anymore."
In a statement early on Thursday from Boston, Mr Romney said: "The results from Iowa caucus night revealed a virtual tie.
"I would like to thank the Iowa Republican Party for their careful attention to the caucus process, and we once again recognize Rick Santorum for his strong performance in the state."