In the 2012 campaign, Vice President Biden has become cheerleader in chief for the operation that killed Osama bin Laden, while claiming that Mitt Romney would not have ordered the mission — which, in Biden’s telling, disqualifies Romney for the presidency.

One problem with that: Joe Biden opposed the mission that killed Osama bin Laden.

During his speech at the Democratic National Convention, Biden lavished praise on President Obama for the bin Laden raid: “Barack understood that the search for bin Laden was about a lot more than taking a monstrous leader off the battlefield; it was about righting an unspeakable wrong, healing a nearly unbearable wound in America’s heart.”He described firsthand how “[w]e sat for days in the Situation Room. He listened to the risks and reservations about the raid. And he asked the tough questions. But when Admiral William McRaven looked him in the eye and said, ‘Sir, we can get this done,’ I knew at that moment Barack had made his decision. His response was decisive. He said do it. And justice was done.”

Then, using an old, out of context Romney quote from 2007, Biden alleged that the GOP nominee would not have done the same. “He was wrong. If you understood that America’s heart had to be healed, you would have done exactly what the President did.”

It turns out, Biden left one important detail out of his account of the Situation Room deliberations — Biden counseled Obama not to do what he did. Alone among the president’s advisers, Biden opposed every option under consideration for killing of Osama bin Laden.

In the new issue of Vanity Fair, Mark Bowden — author of a new book “The Finish: The Killing of Osama bin Laden” — writes: “It was widely reported in the weeks and months after the raid that most, or at least many, of the president’s top advisors opposed the raid. That is not true. Nearly everyone present favored it. The only major dissenters were Biden and [then-Defense Secretary Robert] Gates, and before the raid Gates would change his mind.”

According to Bowden, there were two options on the table for killing bin Laden: a drone strike and the special operations raid. Gates, National Counterterrorism Center director Michael Leiter, and Vice Chairman of the Joint Chiefs of Staff James Cartwright argued for a drone strike. Everyone else favored the special operations raid (including Biden’s own national security adviser, Tony Blinken). But when it was Biden’s chance to speak, he turned to Obama and said: “Mr. President, my suggestion is: don’t go.”

Biden’s reasons were based not on national security, but on electoral politics. “The vice president was never shy about political calculations,” Bowden writes, citing exclusive interviews with Obama and other top officials. “Biden believed that if the president decided to choose either the air or the ground option, and if the effort failed, Obama could say goodbye to a second term.”

After the Situation Room meeting, Gates called the White House to tell the president he had changed his mind and supported the raid. “So in the end,” Bowden writes, “every one of the president’s top advisors except Biden was in favor of immediate action.”

Yet today it is Biden — the lone opponent of immediate action to kill bin Laden — who is painting Romney as unfit for office because he allegedly would have opposed it. There is, of course, no evidence that Romney would not have ordered the bin Laden raid. But we now know for certain that, were it up to Biden, the raid would not have gone forward.

Of course, Biden’s opposition to the bin Laden operation is not surprising. The fact is Biden has a near-perfect record of being wrong about almost every major foreign policy question that the United States has faced in the past three decades. He supported the nuclear freeze in the 1980s, opposed ballistic missile defense and warned of a new arms race if the United States withdrew from theAnti-Ballistic Missile Treaty (we did, and no arms race ensued). He opposed aiding the Nicaraguan democratic resistance that helped roll back communism in our hemisphere, the Reagan defense buildup that bankrupted the Soviet Union, the first Gulf War that liberated Kuwait, and the 2007 surge that turned back the insurgency and defeated al-Qaeda in Iraq. With this record, it is no shock that Biden opposed the killing of bin Laden as well. But it takes chutzpah for Biden to publicly castigate Romney for his imaginary opposition to the bin Laden operation, when Biden actually opposed the bin Laden operation.

Biden is fond of pointing out Romney and Paul Ryan’s lack of foreign policy experience. And it’s true, Biden does have a lot more experience than the GOP nominees — experience at being wrong. Let’s see if in Thursday’s vice presidential debate, Biden dares to repeat his now famous line, “GM is alive, and Bin Laden is dead.” If he does, Ryan can simply answer, “Bin Laden wouldn’t be dead if you had your way, Joe.”

Marc A. Thiessen, a fellow with the American Enterprise Institute, writes a weekly online column for The Post.