BOSTON -- An energized Gov. Mitt Romney told supporters Tuesday that his campaign for president will go on after winning the Massachusetts Republican primary, even though he came up short in several other Super Tuesday contests across the nation.

"I think there are some people who thought it was all going to be done tonight, but it is not all done tonight. We are going to keep on battling," Romney said, reassuring voters gathered at the Boston Convention and Exhibition Center that he has not given up the fight.

With all Bay State precincts reporting, Romney had 51 percent of the vote to Sen. John McCain's 41 percent. Former Arkansas Gov. Mike Huckabee was third with 4 percent, and Rep. Ron Paul was fourth with 3 percent.

"There was a special feeling in my heart when I realized the three places Ann and I have lived have all voted for us -- Michigan, Massachusetts and Utah," Romney said Tuesday night.

Romney also won early contests in Wyoming, Nevada and Maine.

According to a WCVB-TV and TheBostonChannel.com exit poll, 45 percent of Republican voters in Massachusetts cited the economy as the most important issue in their decision, and 62 percent of those voters said they thought Romney was the most qualified candidate to manage the economy.

The exit poll, conducted by Edison Media Research, surveyed 355 Massachusetts Republicans who voted on Tuesday.

Before returning to his home in Belmont to vote, Romney spent the last days before Super Tuesday criss-crossing the country rallying last-minute support. Nationally, he is in a tight race with Republican rival McCain for the party nomination. But with millions of voters in 21 states casting ballots in Republican contests on Super Tuesday, McCain emerged as the clear front-runner.

With 170 delegates, California could be the make-or-break state and Romney hopes his conservative credentials will resonate with voters there. In addition to Massachusetts, Romney also won Utah and Montana, and was counting on the support from several other states.

"I think what you're seeing in our party is that there's a coalescing of support around my candidacy because a lot of people don't want to take the left turn that would be represented by John McCain becoming our nominee," a confident Romney said Tuesday.

But if a large enough number of Super Tuesday delegates do not swing Romney's way, he said several factors will be considered before he decides his next campaign move.

"What is Gov. Huckabee going to do? That might change things. What does our fundraising look like? What does John McCain's fundraising look like? And what are we hearing from leaders in the party, the conservative world? All those things would probably factor into my decision," Romney told supporters gathered in West Virginia.

McCain, leading in the national polls 2-1, spent time in California before heading back to his home state of Arizona on Tuesday.

"We're going to win New York today and we are going to win New York in the general elections. I am going to carry (California), and we are going to campaign all over this magnificent state. We're not going to give it up to anybody," McCain said.

Huckabee has been a thorn in Romney's side since the Iowa caucus, chipping away at his support in southern states and California. Analysts say Huckabee hopes that Super Tuesday results are so muddled that the nomination fight will continue on for at least a few more months.

"What kind of person do you want in the White House? A person who understands the real world of everyday Americans or somebody who has to wait a few months until it finally trickles up to him, before they finally get the message?" Huckabee asked supporters.

In all, 1,023 Republican delegates are up for grabs on Tuesday, with eight of the states being winner-takes-all contests. A Republican candidate needs 1,191 delegates to secure the party nomination. Massachusetts has 43 Republican delegates.

On the Democratic side, Sen. Hillary Clinton held on to her lead in the polls to take the Democratic primary victory over strong challenger Sen. Barack Obama. Both candidates have predicted that Super Tuesday will only keep their rivalry alive.

More than 1,600 delegates are up for grabs on the Democratic side in 24 contests, but it's looking more likely that neither candidate will win enough delegates to decisively claim front-runner status.

Click here for a look at the Democratic race.