Oxon Hill, Maryland: In his first major speech since his US presidential defeat, Mitt Romney urged fellow Republicans Friday to buck up and set course for the White House, as he sought to uplift conservatives.

Despite sharing a bill with a parade of charismatic potential 2016 Republican candidates, the man who lost last year's election to President Barack Obama proved to be the highlight of the middle day of the CPAC confab.

He told a crowd of thousands that he remains optimistic about their movement and will help them return to power in Washington after the Obama era.

"It's fashionable in some circles to be pessimistic about America, about conservative solutions, about the Republican Party," Romney told thousands gathered at the annual CPAC just outside Washington.

"I utterly reject pessimism," he declared. "We may not have carried November ... but we haven't lost the country we love. And we have not lost our way."

Romney was warmly received at the meeting, despite some of CPAC's most right-wing delegates having last year cast doubt on his conservative credentials as a former governor of liberal-leaning Massachusetts.

"I'm sorry I won't be your president, but I will be your co-worker and I'll work shoulder to shoulder alongside you," Romney said to a standing ovation.

The future of the Republican Party is the unmistakable undercurrent of the three-day CPAC confab, with debate over whether a rift among conservatives is bridgeable ahead of the 2014 mid-term elections and the 2016 presidential race.

Last year's loss triggered a Republican family feud, with some conservatives intent on excommunicating leaders when they break with party orthodoxy, such as its stand on taxes or abortion.

Others are concerned that the demand for such ideological purity will only marginalize Republicans at the ballot box.

Even as other speakers before him, including the flamboyant real estate tycoon Donald Trump, sought to dissect his campaign failures, Romney stayed above the fray in his CPAC speech.

"He was very gracious to the conservatives," Monty Lankford, a Republican political coordinator from Tennessee, told AFP after Romney's speech.

"Today he connected with a lot of people and hopefully built some bridges where maybe there weren't bridges before."

While Romney slipped back into campaign mode on a few occasions, urging Republicans to "take back the nation, take back the White House," his speech was more of an honor lap.

A compelling conservative vision could win in 2016, he said, but "as someone who just lost the last election, I'm probably not in the best position to chart the course for the next one."

Several other politicians took up the slack, including Louisiana Governor Bobby Jindal, who raised eyebrows last month when he said Republicans needed to stop acting like the "stupid party."

"We've got to re-calibrate the compass of conservatism," Jindal said.

"We just lost an election. We must not continue to fight on our opponents' terms. The Republican Party must become the party of growth."

CPAC participants have offered a litany of Obama's alleged shortcomings -- exploding the national debt, failing to produce a budget and what they dub a turn toward a nanny state that gets Americans hooked on government handouts.

But Republican Mitch McConnell, the Senate minority leader who vowed in 2010 to "make Obama a one-term president," said he was tired of post-election hand-wringing and implored attendees not to be part of the "crybaby" caucus.

"If you haven't noticed, the folks who won the last election didn't waste much time on a victory lap," McConnell warned.

"These guys are well-organized, they're well-financed, and they're ruthless. And if we don't put this election behind us soon, they're going to eat our lunch again."