(CNN) -- Sen. John McCain could clinch the Republican presidential nomination Tuesday, but Mike Huckabee refuses to call it quits.
Sen. John McCain could pick up enough delegates to clinch the Republican presidential nomination Tuesday.
McCain is 144 delegates shy of sealing the nomination, and 256 Republican delegates are up for grabs Tuesday.
The biggest prizes are Ohio and Texas, where polls show McCain with a comfortable lead. Rhode Island and Vermont also hold contests Tuesday.
Huckabee told reporters the future of his campaign is a fair question if he doesn't take Texas, but he says he believes he has a chance. In Texas, there are 137 delegates at stake.
It would be theoretically possible, but not likely for Huckabee to play spoiler Tuesday, according to CNN senior political analyst Bill Schneider.
"If Huckabee were to win the four states by huge margins, he might be able to prevent McCain from going over the top," Schneider said. "But he'd have to win by pretty solid margins."
Vermont is the only winner-take-all state up for grabs Tuesday, and it has only 17 Republican delegates at stake.
Still, Huckabee says he's staying in the race to help the Republican Party stay true to its core values.
"I do think that many people need to be looking at the future of our party. If we're not reaching out to younger voters, if we're not capturing the issues that people care about ... then we're going to be an extinct party in another few years," Huckabee said on CNN's "American Morning."
Huckabee trails McCain by nearly 800 delegates.
"Everybody acts like we've got to make this decision today. ... What's the hurry? We're six months away from the convention. We're eight months away from the election," he said. Watch Huckabee describe what his party needs to focus on »
The former Arkansas governor spent the weekend making stops across Texas, and he had at least 10 stops between Dallas and Houston Monday.
The Dallas Morning News published an editorial Sunday supporting Huckabee, despite saying he has no chance of winning the Republican presidential nomination.
The newspaper said McCain, who spent more than five years as a prisoner of war in Vietnam, has "long experience and personal courage" and "a solid record of fiscal responsibility."
But the board added that McCain's age, 71, "and his choleric temperament gave us pause, particularly when contrasted to Mr. Huckabee's sunny-side-up brand of conservatism."
According to CNN's "poll of polls" in Texas, McCain leads Huckabee 58 percent to 30 percent.
The Republican Texas poll of polls consists of three surveys: American Research Group (February 29-March 1), Reuters/C-SPAN/Houston Chronicle/Zogby (February 28-March 1), and Belo/Public Strategies (February 26-28).
McCain had three stops scheduled Monday in Texas. On Sunday, he had a barbecue for the media at his Arizona home, and a day earlier he was host for some of his closest political friends, whose public endorsements and private advice helped propel his candidacy.
That guest list included Sen. Mel Martinez of Florida and Minnesota Gov. Tim Pawlenty.
The Arizona senator Monday also picked up big endorsements from Georgia Gov. Sonny Perdue and Mississippi governor and former Republican National Committee Chairman Haley Barbour.
Conservative commentator Rush Limbaugh on Monday encouraged his listeners in Texas to cross party lines Tuesday and vote for Democratic contender Sen. Hillary Clinton in order to "sustain this soap opera."
Replaying a portion of his Friday interview from the "Laura Ingraham Show," Limbaugh said, "We need Barack Obama bloodied up politically."
"I want our party to win. I want the Democrats to lose. They're in the midst of tearing themselves apart right now. It's fascinating to watch, and it's all going to stop if Hillary loses," he said. E-mail to a friend
CNN's Dana Bash, Tasha Diakides and Evan Glass contributed to this report.