Barack Obama is a masterful politician, one of the best in American history. So it’s rather strange that his most important idea about politics is complete nonsense — one which he refuses to ditch after it has repeatedly blown up in his face.

I’m speaking of his belief that partisan divides in America are overstated. He has long deprecated fighting between the parties, and put himself forward as someone who can reverse the long trend toward increasingly vicious partisanship and gridlock. Even after a presidency marked by the most brutal national-level political combat since 1876, he is still promoting the bankrupt idea that compromise and calm discussion can defuse the problems with American politics.

Anti-partisanship has been the major theme of Obama’s entire career in national politics, starting with his famous DNC speech in 2004, where he said: “It is that fundamental belief — I am my brother’s keeper, I am my sister’s keeper — that makes this country work…There is not a liberal America and a conservative America, there is the United States of America.”

It’s Obama at his best, with all his electric charisma. But the sentiment starts to fray on close inspection. That speech was delivered as part of an election in which the Democratic nominee was smeared with accusations he had lied to get his combat medals in Vietnam (a Silver Star, Bronze Star, and three Purple Hearts). The accusations were completely fabricated, but it didn’t stop Republicans from handing out Purple Heart band-aids at their convention.

But four years later, after being elected president on the strength of his immense political talent and disaffection with Republicans due to the ruinous failure of George W. Bush’s presidency, Obama still repeatedly bent over backwards to try to get Republican support for his major legislation. He desperately wanted to get sweeping bipartisan majorities for his stimulus package and health-care reform, but despite offering olive branch after olive branch, he got a bare handful for the stimulus in the Senate and one in the House for ObamaCare. In the latter case, Chuck Grassley played him and Max Baucus for fools, stringing them along with false promises to extract concessions before filibustering the bill anyway.

If it…