Mitt Romney gave a deeply conservative speech Friday at the Conservative Political Action Conference, but those who question the frontrunner’s sincerity said it was all campaign and no conviction.

“It just doesn’t bubble up like it does with Newt or Santorum,” said Shawn Gregg, an attendee from Traverse City, Mich. “He’s not convincing me. I just don’t think he in his heart believes it.”

Hundreds of students and activists gave Romney a standing ovation at the beginning of his speech and another at the end, but the crowd’s reaction was otherwise mixed. A contingent started chanting “Mitt,” when the frontrunner strode on stage, but the cheer didn’t catch on and died after just a few seconds.

On substance, Romney’s speech should have been a home run. He pledged to — among other things — fight for traditional marriage, end federal support for Planned Parenthood, eliminate Obamacare, oppose China’s one-child policy, and shrink the size of government. He name-dropped Edmund Burke and Friedrich Hayek, and said he and Rep. Paul Ryan are on the same page concerning entitlement reform.

But for some listeners, Romney doth protest too much.

“His speech was an exercise in market-tested checklist conservatism — telling the audience what they wanted to hear,” wrote TAS alum Philip Klein in the Washington Examiner.

The unpredictability of this year’s GOP primary has been enough to give poll-watchers whiplash. Amid the turmoil, Romney alone has garnered relatively steady support. But pundits have worried that his support seems to cap out at about a third of the primary electorate.

Texas independent Anne Franklin said Romney was her top choice in 2008, but she’s unsettled that he is apparently unable to close the deal with GOP voters.

“He can’t fire up the base. He’s been running for six years, and all these other people keep surging,” she said. “At the end of the day, when Republicans nominate conservatives, they win. When they nominate moderates, they lose.”

Others aren’t concerned.

For instance, columnist Ann Coulter, who spoke at CPAC earlier Friday, said many on the right seem to object that Romney is a “square.”

“I think we’ve had enough of ‘hip.’ Hip has nearly wrecked the country,” she said. “Let’s try square for a while.”

The sentiment was echoed after the event by NYU student Tanya Belousov, who said Romney understands economics and generally doesn’t stray off message into the clouds. Whatever reservations GOP voters have about Romney now, she thinks they’ll come around.

“The most enthusiastic candidate isn’t the best one,” she said. “Their tepid support will grow warmer as the other people fall away.”

That, of course, assumes Romney himself won’t bleed support after losing Missouri, Minnesota, and Colorado to Rick Santorum earlier this week.

Franklin, the Texan, said she came to CPAC leaning toward Romney. But after hearing half-hour speeches from three of the remaining candidates (Ron Paul did not speak), and after questioning staff from their campaigns, she will leave CPAC as a Santorum supporter.

“I’m convinced now that he’s electable,” she said. “They all have baggage, and I think he can overcome his.”