Biden’s misstep, also in May, in announcing his approval of gay marriage — which forced Obama to do the same before he intended — caused greater disharmony in the White House than was reported at the time.

Biden blamed Campaign Manager Jim Messina for “throwing him under the bus” with the media during the gay-marriage flap — a charge that turned out to be untrue. In an emotional one-on-one meeting with Obama, Biden apologized profusely and said he’d been betrayed by Obama’s aides.

The president tried to calm him down, saying, “Look, Joe, there are people who want to divide us. You and I have to be on the same page from now on. You and I have to make sure that we don’t get divided.”

Plouffe and other West Wingers were even angrier that Biden had screwed up his boss’s carefully laid plans to announce his position before next month’s Charlotte convention — even as Biden previously had counseled against weighing in on the issue for fear of alienating battleground-state independents.