Thirty-four days that decided the election.

The fourth and final installment in POLITICO's Playbook 2012 series once again provides an unprecedented minute-by-minute account of the race for the presidency. The End of the Line follows President Barack Obama and Republican challenger Mitt Romney as their campaign teams go all-in to win in the critical final weeks of the 2012 election.

From Mitt Romney's "47 percent" video to Clint Eastwood's speech to an empty chair, the 2012 presidential campaign did not lack for memorable moments. In The End of the Line, POLITICO senior White House reporter Glenn Thrush and senior political reporter Jonathan Martin chronicle every hairpin turn in a race that defied the predictions of pundits and prognosticators.

While some political observers considered Barack Obama's reelection far from a sure thing, the president and his team remained resolute in their belief that they would prevail. In Boston, Mitt Romney's advisers were just as confident that their man was headed for a smashing victory. In the end, only one of those views would be validated by events. The outcome of this election was never foreordained, however, and would ultimately be determined by two candidates, three debates, and a thousand small but critical strategic decisions.

With an eye toward writing a "first draft of history", Thrush and Martin report on the intense internal debates over ad strategy that defined the parameters of the fall campaign - including a crucial late-May decision by the Obama campaign that may have tipped the scales in the president's favor. They provide a behind-the-scenes look at the candidates' debate preparation sessions, and they reveal why Romney's campaign was so confident they were going to win.