Chris Carlson, File, Associated Press
In this Feb. 7, 2012, file photo Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks during an election night rally in Denver. While Romney didn't finish off rival Newt Gingrich in South Carolina, his failure turn back Rick Santorum in Colorado cost him even more. “A tactical mistake they made was they did try to win Colorado, and failed,” says a longtime GOP presidential campaign strategist, Charlie Black, of the Romney campaign.

The pregame warm-up is over.

Republican presidential candidate Mitt Romney's urgent task now: Learn the lessons of a primary season peppered with tactical and communications errors that cost time and money while reinforcing doubts about him.

Even his allies say that's a must, given that Romney now faces Democratic President Barack Obama's well-oiled machine, battle-tested and prepared to face the eventual Republican nominee.

Romney gave his primary rivals openings with a series of verbal gaffes that highlighted his vulnerabilities. And he let key states like South Carolina and Colorado slip away by failing to anticipate surging opponents.

Since then, Romney aides have huddled in his Boston headquarters mapping out a general election strategy that they'll try to execute with more precision than they did their primary playbook.