FREDERICK, Maryland - After a week of laying off his rivals, GOP contender Newt Gingrich today tore into Mitt Romney, saying, "You can't run a campaign with no principles," and vowing to "go to Tampa" to contest the nomination.

Gingrich showed no signs of quitting the race, arguing that Romney does not have close to the 1,144 delegates needed to secure the nomination and insisting there is still the possibility of an open convention in Tampa.

"I can't tell you today how realistic it is that we will get to an open convention, and I can't tell you today with any certainty that I will be the nominee," Gingrich told a modest crowd in the showroom at a car dealership.

"But I can tell you a couple of things. Despite six years of campaigning, $40 million dollars of his own money, millions raised from Wall Street - largely from people who got our tax money from the bailout - Governor Romney doesn't have it locked down. And we have no obligation to back off and concede anything until he does."

Resurrecting the controversy around the comments by Romney's advisor Eric Fehrnstrom that moving on to the general election would be like resetting an Etch A Sketch, Gingrich swore he would carry on.

"I took very seriously the Etch A Sketch comments of his director of communications. And I know how totally non-value centered political consultants are. … You can't run a campaign with no principles and win the United States," he said.

"You are not going to beat Barack Obama by being clever. And so I want to ensure, and I will be going to Tampa, Callista and I will both be going to Tampa."