Susan Page

USA TODAY

WASHINGTON — In the wake of Bernie Sanders' double-digit victory in the Wisconsin primary, campaign manager Jeff Weaver said Wednesday that a surprisingly strong showing by the Vermont senator in the New York primary in two weeks would disrupt the delegate math that now favors Hillary Clinton.

The home-state battle between the Brooklyn-born Sanders and Clinton, twice elected by the state to the U.S. Senate, could reset the calculations that now see her as the presumptive Democratic presidential nominee, Weaver told Capital Download. And he said the campaign has begun internal discussions about how to handle a contested national convention in Philadelphia in July.

"Obviously, the math is important," Weaver said, acknowledging that Clinton's campaign already describes her numerical lead in delegates as almost insurmountable. "Almost," he emphasized. "But I think too many people are discounting the sort of dynamism in a political campaign and what it means, for instance, if Hillary Clinton were to lose New York in terms of her credibility as a front-runner who's going to represent the Democratic Party in November. I think it would shake a lot of people's confidence."

Even a narrow victory of 51% or 52% "is terribly damaging to her in terms of her credibility in saying, 'I can be the person who can lead this party forward against the Republicans.' "

Capital Download - Conversations with Washington's biggest newsmakers

In recent surveys of likely New York Democratic primary voters, a CBS/YouGov Poll gave Clinton a lead of 10 percentage points, 53%-43%, and a Quinnipiac University poll a lead of 12 points, 54%-42%. Weaver noted that Sanders had been trailing in the campaign's internal polling in Wisconsin as recently as last week, and that he had been down 20 points 10 days before the Michigan primary, a contest he also won.

"Bernie Sanders closes very, very strong," Weaver said. He stopped short of predicting Sanders would win in New York, saying he "may win" but in any any case would "defy expectations" and "do very well."

What each presidential candidate needs to do ahead of New York's primary

Even so, Sanders faces a daunting climb for the nomination despite winning seven of the last eight contests. He has to win two-thirds of the remaining delegates to reach the 2,383 majority needed for nomination; Clinton has to win just one-third of them. "We do certainly have to win the vast majority of the states going forward, there's no doubt about that," Weaver says. "I mean, the math is what it is."

But he told USA TODAY's weekly video newsmaker series that he could see no circumstances in which Sanders would withdraw from the race before the convention in Philadelphia in July, and he suggested the Clinton camp was less confident about the path ahead than they admit.

"I think there's a lot of frustration over there," he said, noting a video that went viral showing Clinton angrily snapping at a questioner on a rope line. "I think her whole campaign is of a similar mindset. I think they're very upset about where they are. They can't conceive that they would ever be in a position where Bernie Sanders would have won seven of the last eight contests and be within 10 points in New York, her home state. It's inconceivable to them."

The sharper tone of Democratic race was apparent in the interview.

Weaver said a front-page headline in Wednesday's New York Daily News that blasted "Bernie's Sandy Hook Shame" was "at a minimum overblown" in criticizing Sanders' vote to give gun manufacturers immunity from liability. "She's been all over the map on guns," he said of Clinton. "She does not have a consistent position on guns, and frankly if she had a different opponent she might have a different position."

He rebuffed Clinton's comment in an MSNBC interview Wednesday that Sanders, who for years has described himself as a democratic socialist, "doesn't consider himself to be a Democrat" — a serious barb, given that only registered Democrats can vote in the New York primary. "Who's a Democrat?" Weaver replied. "The secretary obviously was a Republican at one point, right? Something Bernie Sanders never was." (As a teenager in Illinois, Clinton was a "Goldwater girl" in 1964.)

Hillary Clinton takes to TV to slam Bernie Sanders after his Wisconsin win

Weaver called Sanders "a bold leader" in the tradition of FDR, a New York hero, while he described Clinton as "moderate, incrementalist, centrist" — not words he intended as compliments.

"She has moved, at least in her public stances, very, very close to Bernie Sanders during this race, you know, in an attempt to sort of cut off his support on the left," he said. "But you know were she to win this nomination, she's going to go right back to the center."