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Story highlights

Hillary Clinton's campaign is taking new steps to try and disqualify Bernie Sanders in the eyes of Democratic voters

Clinton took fresh aim at the Vermont senator as part of a new strategy before the New York primary on April 19

Watch CNN and NY1’s Democratic debate, moderated by Wolf Blitzer, Thursday, April 14 at 9 p.m. ET.

(CNN) —  

Hillary Clinton’s campaign is taking new steps to try and disqualify Bernie Sanders in the eyes of Democratic voters, hoping to extinguish the argument that he is an electable alternative for the party’s presidential nomination.

As Sanders took a victory lap following a 14-point triumph in Wisconsin, Clinton took fresh aim at the Vermont senator as part of a three-part strategy before the New York primary on April 19: Disqualify him, defeat him, and unify the party later.

“Some of his ideas just won’t work because the numbers don’t add up,” Clinton told a labor union audience Wednesday in Philadelphia. “In a number of important areas, he doesn’t have a plan at all.”

It’s the latest chapter in Clinton’s approach to Sanders. She’s tried ignoring him, brushing him aside, gently dismissing his policies. The Clinton campaign has refrained from going nuclear on Sanders, aides say, in large part to keep at least some good will alive in hopes of unifying the party at the end of the primary fight.

READ: Clinton on Sanders: ‘I’m not even sure’ he is a Democrat

No more, a top adviser told CNN. The fight is on. Extending an olive branch to Sanders’ supporters “will come later,” an adviser said.

It’s a new moment in this Democratic primary fight, with the Clinton campaign poised to dramatically escalate its criticism of Sanders in the coming days.

Both sides are bracing for a rough-and-tumble contest in New York, with the Sanders campaign already telegraphing its plan to aggressively go after Clinton and her policies. Aides to Clinton said they were simply going on defense, a step needed even more in the wake of their double-digit loss in Wisconsin.

A Clinton campaign fundraising appeal after the Wisconsin primary offered a glimpse into the new approach. The campaign’s deputy communications director, Christina Reynolds, argued that Sanders is unqualified, sending a full transcript of a New York Daily News editorial board interview of Sanders.

“We’ve said for a long time that this primary is about who’s really going to be able to get things done. And from reading this interview, you get the impression Senator Sanders hasn’t thought very much about that,” Reynolds wrote. “In fact, even on his signature issue of breaking up the banks, he’s unable to answer basic questions about how he’d go about doing it, and even seems uncertain whether a president does or doesn’t already have that authority under existing law.”

She added: “If you want to know why Hillary’s experience and deep understanding of the issues facing American families matter so much, you should read this.”