Republican presidential candidate Mitt Romney has said he is looking forward to a long nomination race after beating Rick Santorum by the narrowest of margins in the Iowa caucuses.
Mr Romney spoke as a Republican official said that Senator John McCain planned to endorse Mr Romney, a signal from the 2008 Republican presidential nominee to the rest of the party to rally around the former Massachusetts governor.
Mr Romney appeared before supporters late on Tuesday, before final voting returns were announced showing him with an eight-vote margin over Mr Santorum in the first contest of the presidential nominating cycle.
Ron Paul finished third, and Mr Romney congratulated both on their performances. "On to New Hampshire!" he declared shortly before midnight as he prepared to leave Iowa. "We've got some work ahead."
Mr Santorum said his only surprise about the McCain endorsement was that it had not come earlier. "John is a more moderate member of the Republican team, and I think he fits in with Mitt's view of the world," he said on CNN. Mr Santorum endorsed Mr Romney over Mr McCain in 2008 and dismissed a suggestion that Mr McCain was paying him back for that move.
Surrounded by his wife and family at a victory party, Mr Romney ignored barbs from his Republican presidential rivals. Instead, he focused his remarks on Barack Obama, saying the President has mismanaged foreign policy, the economy and the federal deficit. "This has been a failed presidency," he said.
Mr Romney said he is the candidate best equipped to manage the economy, and vowed to scrap Mr Obama's signature healthcare plan. "The President may be a nice guy, but he's just over his head," he said, telling the crowd that his private-sector experience makes him better suited than Mr Obama to create jobs in a downtrodden economy.
Meanwhile, Mr Santorum declared that his strong Iowa showing means it is "game on" for the party's presidential nomination and that he is heading to New Hampshire for round two.
"Thank you so much, Iowa, for standing up and not compromising, by standing up and being bold," he told cheering supporters heartened by his virtual tie with rival Mitt Romney. "This has been an incredible journey - all 99 counties, 381 town hall meetings, 36 Pizza Ranches."
The former senator from Pennsylvania based his showing on strong backing from the evangelicals and social conservatives who play an important role in the state's Republican politics. His victory speech reflected that sentiment: "God has given us this great country to allow his people to be free," he said. "I offer a public thanks to God."