Marco Rubio may have failed to stop Donald Trump in the Republican primaries, but Hillary Clinton’s campaign is taking a page from Rubio’s playbook: They’re labeling Trump a ruthless con artist, which they see as a blueprint for defining their opponent.

The renewed line of attack centers on Trump University, the defunct seminar that’s now the subject of two class-action suits and a civil suit by New York’s attorney general alleging that it defrauded students who paid as much as $34,995 for its “triple elite platinum” program.

“This is just more evidence that Donald Trump himself is a fraud,” Clinton told supporters in Newark, New Jersey on Wednesday. “He is trying to scam America the way he scammed all those people at Trump U.”

Close video The rise and fall of Trump University Donald Trump has been attacking the lawsuits against his now-defunct institution, Trump University. New York Attorney General, Eric Schneiderman, who filed one of the lawsuits in 2013, responds to Trump’s attacks. Donald Trump has been attacking the lawsuits against his now-defunct institution, Trump University. New York Attorney General, Eric Schneiderman, who filed one of the lawsuits in 2013, responds to Trump’s attacks. share tweet email Embed

Earlier, Clinton issued a storm of tweets calling Trump University a “con” and “fraud” that would “target struggling families to fleece them.”

Trump U is back in the news after a Gonzalo Curiel, a federal judge presiding over one of the class action suits, unsealed testimony from former Trump U sales employees. The former staffers claimed they had been told to pressure economically vulnerable clients into taking on credit card debt to work with instructors who had little relevant experience or connection to Trump himself. One of them described it as a “fraudulent scheme” that “preyed upon the elderly and uneducated to separate them from their money.”

Trump denies the charges, pointing to positive survey evaluations from students, although some later told The New York Times they felt pressured to avoid negative statements.

The emergence of Trump U as a campaign issue is an important moment in the race as it fits into a broader framework Democrats have long planned to use against the presumptive GOP nominee. Just as the Obama campaign in 2012 highlighted Mitt Romney’s business record at Bain Capital to portray him as indifferent to economic suffering, the Clinton campaign is using Trump University to depict Trump as a fast-talking billionaire who preys on struggling Americans for profit.

RELATED: Donald Trump’s veterans controversy goes from bad to worse

“Trump U is devastating because it’s metaphor for his whole campaign: promising hardworking Americans way to get ahead, but all based on lies,” Clinton press secretary Brian Fallon tweeted on Wednesday.

In making that case, however, the Clinton campaign is adopting a strategy that never gained traction in this year’s Republican primaries. Rubio made Trump University the centerpiece of his attacks on the mogul while also describing it as a metaphor for the rival’s campaign.

“What he did to them is what he’s doing to voters now,” Rubio said during a February speech in Virginia, referring to the students now suing the school.

Democrats are eager to point out that they aren’t the first to make these points. Fallon, Clinton’s spokesman, retweeted old attacks from Rubio (who has since made his peace with Trump) saying Trump University “duped everyday Americans” and Sen. Ted Cruz, who once tweeted a mock “Certificate of Deception” from the program. Clinton also approvingly retweeted Mitt Romney, who in March described Trump’s campaign promises as “as worthless as a degree from Trump University.”

The question now is whether the controversy around Trump University can work in Clinton’s hands any better than it did with Republicans. In retelling the story of Trump University, Democrats have a few things going for them that Republicans did not.

RELATED: The Trump University train wreck jolts presidential race

The most obvious is a different electorate, one that’s far more inclined to regard Trump with suspicion than the Republican primary voters who had already begun coalescing around his campaign by the time Rubio launched his attack.

But Democrats also have another luxury: time. Rubio and Cruz each made their case against Trump in a state of last-minute panic after losing key contests in February. Before then, Rubio had largely avoided antagonizing Trump and Cruz had actively praised him for months.

With his back against the wall, Rubio in particular took a kitchen sink approach in which he brought up Trump University alongside a whole host of other issues, including Trump’s physical appearance, electability and demeanor.

Close video Is the GOP resigned to Donald Trump? Former New Hampshire Governor John Sununu joins MSNBC’s Steve Kornacki to share whether he’s warming up to Donald Trump and why supporting his party’s ticket is his top priority, regardless of the presidential candidate. Former New Hampshire Governor John Sununu joins MSNBC’s Steve Kornacki to share whether he’s warming up to Donald Trump and why supporting his party’s ticket is his top priority, regardless of the presidential candidate. share tweet email Embed

This was the same period when he famously joked that Trump’s “small hands” might be linked to other physical deficiencies, prompting Trump to reassure a debate audience “there’s no problem, I guarantee.”

The Clinton campaign has jumped in early, rolling out its attacks in concentrated doses, with an army of surrogates and outside groups reinforcing the same theme in the hopes it sinks in with voters.

“Rubio’s strongest moment was when he called Trump a con man based in part on Trump U,” Fallon tweeted on Wednesday. “Rubio wasn’t around long enough to make case. We will.”

The Trump University attack is also likely to stick around in part because it’s a handy Christmas tree to hang related issues the Clinton camp has raised.

Last week, for example, her team launched an all-out effort to highlight past comments by Trump in 2006 and 2007 expressing hope the housing market would crash, which would allow him to buy property at low prices.

In 2009, Trump University advertised a course to “learn how you can profit from the largest real estate liquidation in history.”

RELATED: Court documents reveal how Trump University staffers sold the brand

“Sorry for you if you are being foreclosed, but good for you if you know how to invest,” read notes prepared for a course instructor unsealed by the court.

Trump’s response to the lawsuit also fits into ongoing efforts by Democrats to zero in on Trump’s temperament and penchant for racially inflammatory remarks.

He has repeatedly attacked Curiel, the judge presiding over one of the class-action suits, and devoted more than twelve minutes of a speech last week to decrying Curiel’s alleged unfairness. Trump has notably argued that Curiel is biased because of his Hispanic heritage. Last week, he told supporters Curiel, who was born in Indiana, “happens to be, we believe, Mexican.”

Trump has proven he can survive attacks on his business record in the primaries, but the general election is whole new environment. This story could be the biggest test yet of his ability to translate that success with Republicans to a broader audience.