CHICAGO — This is what “grinding it out” looks like at President Obama’s election headquarters: scores of young staff members intently clicking away at computer keyboards as they crunch gigabytes of data about which way undecided voters are leaning, where they can be reached, and when; strategists standing at whiteboards busily writing and erasing early voting numbers and turnout possibilities; a lonely Ping-Pong table.

The wave of passion and excitement that coursed through Mr. Obama’s headquarters here in 2008 has been replaced with a methodical and workmanlike approach to manufacturing the winning coalition that came together more organically and enthusiastically for him the last time, a more arduous task with no guarantee of success.

As Washington and the cable news commentariat breathlessly discuss whether Mitt Romney’s post-debate movement in the polls has peaked, Mr. Obama’s campaign technicians — and that’s what many of them are — are putting as much faith in the multimillion-dollar machine they built for just such a close race as in the president himself.

“We are exactly where I thought we would be, in a very close election with 12 days left with two things to do and two things only: persuade the undecided and turn our voters out,” said Jim Messina, 43, the president’s technocratic campaign manager, slightly paler and more hunched than he was when the campaign began. Pointing to the rows of personnel outside his office on Thursday, he added, “Everything in that room has been focused on that.”