WASHINGTON --Against overwhelming odds, Mike Huckabee keeps brushing off calls to drop his presidential bid for the good of the Republican Party. The former Arkansas governor and ordained Baptist minister is following in the footsteps of past spoilers such as Republican Ronald Reagan in 1976 and Democratic Sen. Edward M. Kennedy in 1980, who both pressed uphill primary challenges to the limits. Some GOP sages suggest it's hard to quit while you're still winning races, as Huckabee is doing, despite the mathematical reality of the delegate count. But then Huckabee likes to brag that he "didn't major in math, I majored in miracles," and he asserted anew on Monday his intention to stay in the race. In those earlier challenges, the front-runners were sitting presidents. Both President Ford in 1976 and President Carter in 1980 went on to lose their re-election bids, clearly weakened by the divisive primaries. This time there is no incumbent, but Sen. John McCain has a commanding lead. Some Republicans suggest Huckabee's insistence on staying in the race could hinder the party's ability to unify behind the front-runner. President Bush over the weekend praised McCain as a "true conservative," although he suggested the Arizona senator still needed to mend more fences with conservatives, many of whom remain distrustful of him, especially on the issue of immigration. Jeb Bush, the president's brother and former Florida governor, endorsed McCain on Monday. For his part, Huckabee was unbowed on the eve of contests in Virginia, Maryland and the District of Columbia, saying "I still could win. ... Nobody thought the Giants were going to win the Super Bowl, either." Huckabee also picked up the endorsement of one-time rival Rep. Duncan Hunter, R-Calif. Huckabee says he'll drop out if he's mathematically eliminated -- in other words, once McCain racks up the needed 1,191 delegates. But that probably can't happen until April 22, when Pennsylvania votes. For practical purposes, McCain already appears beyond Huckabee's reach. According to the latest count by The Associated Press, McCain had 729 delegates to Huckabee's 241 delegates. One factor keeping McCain from claiming a majority sooner is that Romney has yet to release his 288 delegates. Still, McCain suffered embarrassing losses to Huckabee in Louisiana and Kansas this past weekend -- and a narrow win in Washington state that is being contested by the Huckabee campaign. Other major challengers have dropped out. Former Massachusetts Gov. Mitt Romney suspended campaigning last week "for our party and our country," saying to stay in would only strengthen whichever Democrat gets the nomination -- either Sen. Hillary Rodham Clinton or Sen. Barack Obama. Huckabee makes no such argument. He says most of those clamoring for him to drop out are McCain backers. Asked whether Huckabee risks overplaying his hand, his campaign chairman, Ed Rollins said he didn't think so. "I think he's made it very clear that until either he or McCain have 1,191 delegates, he's going to stay in this thing. We always wanted to get it down to one-on-one," Rollins said Monday. "This is what he wants to do. Getting Romney out of the race obviously eliminates a guy who had an advantage with money." Huckabee and McCain "respect each other. They're both men of integrity," Rollins said. "Tomorrow is a big day. We'll keep going as long as we can." Texas Rep. Ron Paul also remains in the race. Gone are former New York Mayor Rudy Giuliani, once considered the GOP front-runner, and actor and former Tennessee Sen. Fred Thompson, the favorite of many conservatives. Consultant Rich Galen, who worked for Thompson but now is unaffiliated, said Huckabee "has still got money and he's having a good time. He's not conducting a negative campaign. He could go on to be recognized as the leader of the conservative wing of the Republican Party." Greg Mueller, a conservative Republican consultant not associated with a candidate, said Huckabee is helping to burnish his own reputation as perhaps "the next man in line" for Republicans in a future contest "so long as he's amassing delegates." "With Romney out of the race, Huckabee became a repository for the anti-McCain vote. I think for conservatives, it doesn't hurt for a while here to make sure Senator McCain and his folks understand that the fissures that conservatives have with Senator McCain didn't happen overnight, and are not going to be resolved overnight," said Mueller. "One of the reasons Huckabee is staying in is to give a voice to conservatives so that we are a very strong presence going into the convention." Mueller worked for Pat Buchanan in the conservative commentator's 1992 primary challenge against then-President George H.W. Bush. Huckabee is not supported by all conservatives. Conservative activist Gary Bauer backed McCain on Monday, citing McCain's anti-abortion record "and demonstrated commitment to the values that keep our families and communities strong." Huckabee complained that many Republican leaders are trying to turn the process into a coronation for McCain. "There's a growing chorus of establishment Republicans to sort of call the game here," Huckabee told about 100 supporters in Richmond, Va., Huckabee hopes he can add Virginia to his list of Southern victories, but polls suggest McCain is leading. McCain said he expects Huckabee to stay in the race. "I respect Governor Huckabee. I expect him to stay in the race. I know we've got a sizable lead in delegates, but we're not easing off," McCain said Monday in Richmond, Va. "Governor Huckabee has every right to remain in the race as long as he feels is necessary." Reagan waged an all-out challenge to Ford in 1976, carrying his battle nearly all the way to the GOP convention in Kansas City and even announcing a prospective running mate -- then-Sen. Richard Schweiker of Pennsylvania. While the strategy failed, the former California governor's challenge paved the way for a conservative vice presidential running mate, Sen. Bob Dole, R-Kan. The ticket was defeated by Democrat Jimmy Carter. Carter, in turn, was challenged by Kennedy as the former Georgia governor sought a second White House term in 1980. Although Kennedy eventually bowed out of the race, he stirred up party delegates with a rousing speech at the Democratic convention. Carter lost to Reagan.