NEW YORK, NY - APRIL 09: Democratic presidential candidate Hillary Clinton holds a Latino organizing event on April 9, 2016 while campaigning in the Brooklyn Borough of New York City. The New York Democratic primary is scheduled for April 19th. (Photo by Andrew Renneisen/Getty Images)

As the Sanders surge continues, the Democratic presidential contest has gotten

chippy. After Clinton called Sanders "unprepared" to be president, Sanders responded he thought she was "unqualified."

The chattering classes went off. Democrats were rending garments and ringing hands worried about the campaign getting too negative and personal. Guy Cecil, director of one of the Clinton armory of SuperPacs, played the inevitable sexist card. President Obama felt it necessary to weigh in, with his spokesman Eric Schultz saying Obama believes Clinton" comes to the race with more experience than any non-vice president in recent campaign history." More experience, in other words, than anyone except Al Gore, daddy Bush and Richard Nixon.

But the kerfuffle was all nonsense. Sanders doesn't think Clinton is "unqualified," as he quickly acknowledged. He has repeatedly paid respect to her experience and qualifications. And the rhetorical misstatement frankly wasn't all that harsh. Qualifications haven't been the centerpiece of the Sanders-Clinton race, but they were in the Clinton-Obama face-off in 2008. They didn't differ all that much on ideology or program. Clinton's major attack on Obama was that he was simply unqualified. Remember the ad with the ominous call at 3:00 in the morning? And for harsh rhetoric, Sanders' misstatement was nothing compared to Clinton's scorning Obama in comparison to her and their putative Republican opponent, John McCain. Senator McCain, she said, "will put forth his lifetime of experience. I will put forth my lifetime of experience. Senator Obama will put forth a speech he made in 2002." Ouch.

Sanders' critique of Clinton isn't that she is unqualified or inexperienced. It is far tougher and more substantive. His campaign is premised on the belief that she is too compromised and conservative to be the president we need. It isn't about character or experience; it is about direction, program and independence.

Sanders argues that our economy is rigged to favor the few, and our politics is corrupted by the big money, special interests and revolving door appointments that keep fixing the game. He argues we need fundamental change, not simply piecemeal or incremental reform if we are to make this economy work for working people once more.

Sanders is running because he believes that Clinton is too compromised in her agenda. He has defined major substantive areas of disagreement: on corporate trade policies, on the need for major public investment and a sweeping initiative to take on global warming, on national health care, on breaking up the big banks and curbing Wall Street, on progressive taxation that will pay for tuition free public college, on $15.00 an hour minimum wage and empowering workers to organize, on dialing down our interventionist foreign policy and more.

Clinton has moved to adopt a bolder reform position this year than in 2008 or before. She's basically at one with President Obama's policies. Yes, she's come out against the president's Transpacific Partnership deal, but everyone believes that is just campaign positioning. She claims to be tough on Wall Street, but even her Wall Street donors don't believe her. She's assiduously avoided embracing the Warren-Sanders reform agenda. She's put forth a good agenda on global warming, but opposes putting a price on carbon, opposes banning fracking, and hasn't made climate change a centerpiece of her campaign. She's scorned Sanders call for national health care or for tuition free college. She's been a supporter of the regime change follies from Iraq, to Honduras to Libya to Syria to the Ukraine.

Sanders also argues that Clinton is too compromised by the big money that is central to financing her campaign. He decided to forego any SuperPacs and to crowd source the financing of his campaign because he believes that big money compromises candidates. Clinton claims this insults her character. But everyday experience and a legion of academic studies prove that money perverts our politics, that the wealthy and the entrenched interests get their way, even when the majority are opposed. It's nice to blame Republican obstruction, but the heart of the economic policies that are failing working people - corporate trade deals, deregulation, skewed and loophole ridden tax code, starved public investment, corporate subsidies and crony capitalist arrangements and much more - enjoy bipartisan support.

Clinton harshly attacked Obama as unqualified in 2008. But the harsh rhetoric didn't get in the way of the party uniting in the fall. Whatever the differences inflated for the primaries, the two basically agreed on politics and policies. And, of course, both were both funded by similar deep pockets.

Sanders has been -- despite all the fretting inside the beltway -- a remarkably courtly opponent to Clinton. He hasn't unleashed oppo research on the numerous Clinton scandals. He's irate about her distorting his record - on guns, on the auto bailout, on the crime bill -- but he's largely kept his focus on the substantive differences between them. This includes the indictment on how she funds her campaigns and her collecting millions in speaking fees from Wall Street banks and other corporate interests -- an argument central to the case he is making.

Despite the relative mannerliness of the Democratic race, bringing the party together after the primaries won't be easy. Sanders has built a movement that is challenging the fundamental direction of the country and the central way the party does business (and business does the party). Those differences are much harder to paper over than personal insults issued by tired candidates in the New York hothouse. Both Sanders and Clinton will endorse whomever becomes the nominee, but Democrats will need a wingnut Republican opponent to help unite the party in the fall. Luckily, Republicans seem intent on serving one up.