The Clinton campaign is saying that they won't agree to a debate with Bernie Sanders in New York because they're offended by Sanders's recent "tone."

This is plainly ridiculous.

The reason Clinton's people don't want a debate before the New York primary is there's no upside for them in a debate before the New York primary. Their polling, as of now, shows Clinton winning the state's massive delegate haul, and a debate would simply be an opportunity to screw that up.

The problem is that their reasoning, though tactically correct, would strike people as rather less than sporting. So the Clinton campaign has come up with the argument that Sanders has somehow crossed a line with his negative campaigning. "They’re talking about running harsher negatives now," Joel Benenson, Clinton's pollster, complained to CNN.

This is flatly absurd. The Democratic primary — including the debates — has been substantive and respectful. Sanders has, at times, bent over backward to run a positive race, as when he refused to hound Clinton over her emails. If any candidate has ever proven himself a fair and courteous adversary, it's Sanders. The mockery Sanders's supporters are throwing at Clinton is entirely merited.

This is the Clinton campaign at its worst. The argument isn't just false, it also insults the intelligence of voters. The message is that debates are something Clinton graciously concedes to rather than participates in as part of the democratic process. And the whole effort baits and annoys the Sanders supporters whom Clinton ultimately needs to win over.

Politics ain't beanbag. If the Clinton campaign doesn't want another debate, no one can force them into it. But if they didn't want another debate, they should have just said so, and offered some anodyne excuse like they wanted to spend more time campaigning in New York and less time campaigning on television. Trying to place the blame on Sanders for the fact that they are refusing to debate is just dirty, and it cheapens the tone of this race far more than anything the Sanders campaign has done recently.