Making only passing mention of the campaign behind him, 2012 GOP presidential candidate Mitt Romney delivered his vision for the future of the Republican Party and the country on Friday at the Conservative Political Action Conference in a speech billed as a thank you to his supporters.

"I’m sorry I won’t be your president, but I will be your co-worker, and I’ll work shoulder to shoulder besides you," said the former Massachusetts governor, who recently returned to the private sector.

Romney didn't dwell on the 2012 campaign or offer any specifics about what happened, but he did concede that his campaign wasn't flawless.

"It's up to us to make sure that we learn from our mistakes — and my mistakes," he said.

Since the end of the race, some conservatives have criticized Romney's campaign for its shortcomings and Romney for his gaffes. But the crowd at CPAC was nothing but gracious and gave Romney loud ovations as he entered and exited the stage.

Romney got some backup before he even took the stage, as South Carolina Gov. Nikki Haley (R) roiled up the crowd and urged them to cheer on their 2012 candidate. Romney and Haley have had a close relationship ever since she was first elected governor in 2010.

"This is a leader who's back to tell you thank you," Haley said before imploring the crowd to give him a big welcome.

Romney said he doesn't feel pessimistic after losing the 2012 race, and in fact that the experience -- his second failed presidential campaign but his first time as the GOP candidate -- reinforced and furthered his faith in the American people.

“Of course I left the race disappointed that I didn’t win," he said. "But I also left honored and humbled to represent the values we believe in and to speak for so many good and decent people.”

He said the GOP, which is left searching for a new identity after his loss, would be just fine.

“It’s fashionable in some circles to be pessimistic about America, about conservative solutions, about the Republican Party," Romney said. "I utterly reject pessimism.”

Romney acknowledged that the crowd probably wasn't interested in his prescription for the future -- “As someone who just lost the last election, I’m probably not in the best position to chart the course for the next one" -- but he did urge the party to focus more on its success in state government, specifically when it comes to the 30 GOP governors across the country.

He said he remains optimistic that the party that has lost the popular vote in five of the last six presidential elections will be back on top soon enough.

“In the end, we’ll win for the same reason we won before: because our cause is just, and it’s right," Romney said.