The Democratic party's race is much tighter, with Barack Obama, the Illinois senator, and Hillary Clinton, New York senator, nearly tied in the count for the party's nomination.
Huckabee said during a conference of conservative activists that he would continue his shoestring presidential campaign, which has made inroads with social and religious conservatives.
"Am I quitting? Let's get that settled right now. No, I'm not," he said.
McCain, an Arizona senator, appears almost certain to win the nomination after his chief rival, Mitt Romney, a former Massachusetts governor, dropped out on Thursday.
Huckabee is now his only major opponent and is running a distant second.
McCain has gathered more than 700 of the 1,191 delegates needed to win the Republican nomination at this summer's nominating convention.
But McCain still faces widespread opposition from conservatives unhappy with his views on immigration, tax cuts and other issues.
The win for Huckabee followed a strong showing in the South earlier in the week, when the Baptist minister won four Southern states and West Virginia in Super Tuesday voting that involved nearly half of the American states.
"I did not major in math, but I majored in miracles, and I still believe in them," Huckabee said later at a rally at the University of Maryland.
On Saturday, Clinton and Obama face off in contests in Nebraska, Louisiana and Washington, which have a combined total of 194 delegates for the taking in a Democratic race where every delegate has become crucial.
Both campaigned in Maine, which has a contest on Sunday, and will appear on Saturday night at a Virginia Democratic party fundraising dinner. Virginia votes on Tuesday.
|Obama and Clinton face off in contests in Nebraska, Louisiana and Washington [AFP]|
During her stop in Maine, Clinton took aim at McCain and touted herself as the Democratic candidate with the experience to beat him in November.
"I can go toe-to-toe with Senator McCain on national security," she said.
Huckabee took a veiled swipe at Clinton at the conservative meeting, noting that in Arkansas, he was "the only person who's ever run against the Clinton political machine and beat it".
Clinton's husband, former US president Bill Clinton, preceded Huckabee as Arkansas governor.