Mike Huckabee's pledging to stay in the race, but he plans to veer sharply off the campaign trail this weekend to give a paid speech in the Cayman Islands.

The surprise announcement came after John McCain beat the former Arkansas governor in the District of Columbia, Maryland and Virginia primaries Tuesday night, virtually assuring him the GOP nomination.

"We're not giving up," Huckabee campaign manager Chip Saltsman said on the plane from Little Rock, Ark., to Wisconsin, where Huckabee was campaigning ahead of the state's primary next week.

But Saltsman said the Cayman Islands speech was booked six months ago, and that Huckabee would be there from Friday through Sunday morning, when he would return to Wisconsin.

The campaign did not disclose where Huckabee would be delivering the speech, but FOX News found out it will be at the Young Caymanian Leadership Awards banquet in Grand Cayman, where he spoke several years ago.

Asked about the odd timing, Huckabee said he simply needs a paycheck.

"I'm the only person who doesn't get paid by the taxpayers to campaign ... I have to pay for (other candidates') Senate salaries even if they are not on duty. The taxpayers aren't paying a dime for me to campaign and I don't take anything from my campaign so I have to make a living. I do that through my writing and my speaking ... There will be a few more times when I've got to go out and make sure I can make my mortgage payments just like everybody else has to do. I am not independently wealthy."

McCain's campaign claimed after Tuesday's results came in that it was mathematically impossible for Huckabee -- with 242 delegates to McCain's 843 -- to reach the needed 1,191 delegates to clinch the nomination.

But Huckabee said Tuesday night "there is still a sense in the Republican Party to have a choice."

He repeated his pledge that the nomination is not secured until one candidate reaches the 1,191 delegate mark.

FOX News' Serafin Gomez contributed to this report.