One of the gravest errors, many say, was the Romney team’s failure, until too late in the campaign, to sell voters on the candidate’s personal qualities and leadership gifts. The effect was to open the way for Obama to define Romney through an early blitz of negative advertising. Election Day polls showed that the vast majority of voters concluded that Romney did not really care about average people.

These failures are now the subject of scrutiny by national GOP ­officials who say they plan to “reverse engineer” the ­Romney effort to understand what went wrong. A number of Romney’s top aides stressed in interviews that, while they ­remain proud of their work, they feel an obligation to ­acknowledge their numerous mistakes so lessons are learned.

Rich Beeson, the Romney political director who co­authored the now-discredited Ohio memo, said that only after the election did he realize what Obama was doing with so much manpower on the ground. Obama had more than 3,000 paid workers nationwide, compared with 500 for Romney, and hundreds of thousands of volunteers.

“Now I know what they were doing with all the staffs and ­offices,” Beeson said. “They were literally creating a one-to-one contact with voters,” something that Romney did not have the staff to match.