BOSTON — Former Gov. Mitt Romney had enough goodwill left among fellow Massachusetts Republicans to carry him past rival John McCain, while the race between Democrats Barack Obama and Hillary Rodham Clinton was too close to call.

Romney, criticized for treating Massachusetts as a stepping stone to higher office while governor, won his home state by finding favor with voters who support him on immigration and the economy, according to exit polls conducted for The Associated Press.

"It's touching to have folks remember us fondly," Romney said after voting Tuesday in Belmont.

The Associated Press made its call based on surveys of voters as they left the polls.

Republican Mary Jordan of Topsfield said she didn't decide to vote for Romney until she entered the voting booth.

"I think he's the least unlikeable. I really didn't like any of them," Jordan, a 43-year-old teacher's aide, said of a GOP field that also included former Arkansas Gov. Mike Huckabee.

Exit poll results showed that close to half of all voters in both parties cited the economy as the most important challenge facing the nation. For Democratic voters, the war in Iraq placed a close second. For Republican voters, immigration placed second.

The Clinton-Obama race split the Massachusetts Democratic establishment as well as voters.

Sen. Edward Kennedy summoned memories of his brother the slain president when he endorsed Obama a week ago, and Gov. Deval Patrick has campaigned hard for his fellow Chicagoan.

Meanwhile, Clinton was bolstered by support among rank-and-file state lawmakers, as well as Senate President Therese Murray, who has suggested Clinton lost key endorsements in part because she's a woman, and House Speaker Salvatore DiMasi, who is often at odds with Patrick.

John Stephen Dwyer, a 40-year-old education coordinator from Boston, said he voted for Obama.

"I like his optimism," Dwyer said. "I like his boldness on environmental issues I like his consistency in not supporting our military action overseas."

Bob Poland, 49, said he chose Clinton based on her experience.

"Obama seems like a nice guy, but I'm just worried he doesn't have enough experience to be president," said Poland, a travel agent who also cited Clinton's stance on health care and economic issues.

Massachusetts may seem like the ultimate Democratic stronghold, but the single largest group of voters here are independents, who comprise half the state's 4 million voters and can cast ballots in either party primary. Registered Democrats account for nearly 37 percent and Republicans make up 12 percent.