(CNN) -- Calling himself an "authentic" conservative, Mike Huckabee appealed Thursday for supporters of Mitt Romney to follow him instead of GOP front-runner Sen. John McCain now that Romney is out of the race.
Huckabee is the sole top-tier candidate challenging McCain for the Republican presidential nomination.
"This is a two-man race for the nomination, and I am committed to marching on," Huckabee said in a statement, emphasizing his belief in a strong national defense, his anti-abortion stance and his support for tighter border security.
"As a true authentic, consistent, conservative, I have a vision to bring hope, opportunity and prosperity to all Americans, and I'd like to ask for and welcome the support of those who had previously been committed to Mitt," he said.
Huckabee faces a daunting challenge. McCain, an Arizona Republican, has a significant lead in the delegate count after Super Tuesday. According to CNN calculations, Huckabee has 181 delegates to McCain's 714.
Romney and McCain furiously challenged each other's conservative record before Super Tuesday, and McCain's positions on immigration, campaign finance reform and energy policy have angered many conservatives.
McCain also infuriated many conservatives when he sponsored a comprehensive immigration bill with Massachusetts Sen. Edward Kennedy. Many conservatives labeled the McCain-Kennedy bill "amnesty" for illegal immigrants when it was introduced last summer.
Huckabee is hoping those conservatives unhappy with McCain will shift their support to him.
"The people of this country need a choice, and right now I'm gonna be their choice," Huckabee told TV host Tyra Banks Thursday. "I'm gonna be the choice for all those people who don't think Washington has all the answers, for all those people who think that somebody who is not a part of that establishment needs to represent our party and the American people."
The former Arkansas governor will have opportunities to test his strategy soon. Louisiana Republicans will vote in a primary and Kansas Republicans will hold caucuses Saturday. Next Tuesday, Virginia, Maryland and the District of Columbia voters will head to the polls for the "Potomac primaries."
Many conservatives have also questioned Huckabee's conservative record. He drew the ire of fiscal conservatives when he agreed to raise taxes while governor.
And don't expect conservative radio talk show host Rush Limbaugh, who has been one of the most vocal of McCain's critics, to hop on Huckabee's bandwagon anytime soon. During his radio show Thursday, Limbaugh indicated he did not view the former Arkansas governor as a "conservative alternative" to McCain.
"There is no conservative alternative in the race," Limbaugh said. "It's just that simple."
But Huckabee's Super Tuesday surprise victories in five Southern states buoyed his campaign, and some Republican strategists say the fact Huckabee pulled off those with with far less money than his rivals can't be discounted.
"Huckabee will do reasonably well with some conservatives, and he's run, to his credit a very good campaign," said David Winston, a Republican strategist. "I just don't think he's in a position to really take on McCain by any stretch of the imagination at this point." E-mail to a friend