DES MOINES, Iowa (AP) _ Front-running Republican presidential candidate Mitt Romney focused on friendlier political territory in New Hampshire on Wednesday, moving on from the Iowa caucuses where he managed only the skimpiest of victories in the first-in-the-nation vote to pick a challenger to President Barack Obama.

Just eight votes separated Romney, the former Massachusetts governor, from former Pennsylvania Sen. Rick Santorum. Santorum staged an abrupt rise from single-digit support in the Midwestern state to become the patrician Romney’s strongest competitor for the Republican nomination. The race will play out over the next six months in primary elections and caucuses nationwide before the November election. New Hampshire votes Tuesday.

“I’ve got a big target on me now,” Romney said. “I’ve got broad shoulders. I’m willing to handle it.”

Romney has by far the most extensive national campaign operation and is much better financed than any of the other Republican contenders.

The Iowa results, while not a clear win for Romney, most likely will only extend the time he needs to accumulate sufficient delegates to become the party’s nominee. But Santorum’s strong showing suggests Romney will have to battle through many more primary elections and state caucuses before he can seal the nomination.

Minnesota Rep. Michele Bachmann, meanwhile, announced on Wednesday that she was withdrawing from the race after finishing last in Iowa.

Bachmann, an extreme conservative, spoke at length about her reason for entering the race: congressional passage of Obama’s overhaul of the U.S. health care system. She said it “endangered the very future” of the United States.

Texas Gov. Rick Perry, who finished fifth in Iowa, declared his intention to continue campaigning. It was widely believed he, too, would leave the race, but he wrote on his Twitter feed Wednesday: “Here we come South Carolina!!!”

Perry’s camp said he would be at Saturday’s Republican debate in New Hampshire, but he intends to focus on South Carolina’s primary on Jan. 21.

As the Iowa returns were counted, they showed a near tie through most of Tuesday night and into early Wednesday among Romney, Santorum and Texas Rep. Ron Paul. Hours after the polls closed, Iowa Republican chairman Matt Strawn reported that Romney had 30,015 votes, with 30,007 for Santorum, whose fortunes were carried by his appeal to the state’s evangelical Christians and social conservatives in a state that is largely farmland and 91 percent white.

The count from all 1,774 precincts showed Romney with 24.55 percent support and Santorum with 24.54 percent. Paul, who drew a younger crowd with his libertarian views, drew 21.5 percent of the votes.

The chaos that has marked the early months of the Republican race has diverted attention from Obama, who is vulnerable in his bid for a second term because of the stagnant U.S. economy and high unemployment that lingers from the 2007-2009 Great Recession.

Before his victory was announced, Romney added to his already-formidable national network by announcing the endorsement of Sen. John McCain, who twice won the New Hampshire primary and was the Republican nominee in 2008. Romney accepted the endorsement in a joint New Hampshire appearance Wednesday afternoon.

Romney’s campaign has failed to catch the imagination of the Republican base. Those voters have grown ever more conservative in recent years and view him with grave distrust for having taken moderate positions in the past. But Romney is the favorite of the party establishment, which sees him as the candidate best equipped to defeat Obama.

Romney on Tuesday became the first candidate to purchase television advertising in Florida, whose primary is Jan. 31. He is spending $264,000 on television advertising in New Hampshire, $260,000 in South Carolina and $609,000 in Florida, according to figures obtained by the Associated Press.

Santorum, meanwhile, struggled to pay for campaign transportation in recent days. He’s spending just $16,000 to air a television ad on New Hampshire cable stations this week.

In a sign of the acrimony ahead, Santorum said the McCain endorsement was to be expected. “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.

Even before his victory was announced, Romney looked past his Republican rivals and took aim at Obama. “The gap between his promises four years ago and his performance is as great as anything I’ve ever seen in my life,” he told supporters.

In all, more than 122,000 straw ballots were cast, a record for Iowa Republicans, and the outcome was a fitting conclusion to a race as jumbled as any since Iowa gained the leadoff position in presidential campaigns four decades ago.

The results are nonbinding when it comes to picking delegates to the Republican convention next summer. But an Associated Press analysis showed Romney would win 13 delegates and Santorum 12 if there were no change in their support as the campaign wears on.

Former House Speaker Newt Gingrich was fourth after a recent and dramatic rise and fall in the polls. Both men vowed to carry the fight to New Hampshire’s primary next Tuesday and beyond.