Hillary Clinton and Bernie Sanders opened a series of fresh and fierce attacks against one another on Monday on issues ranging from immigration to fracking as they campaigned across New York ahead of the state’s contentious primary.

Campaigning in the New York City borough of Queens, Clinton assailed Sanders for his mixed record on immigration reforms and said he’s struggled to detail his positions on foreign policy and financial regulation.

“I have noticed that under the bright spotlight and scrutiny here in New York, Sen. Sanders has had trouble answering questions,” she told reporters after a campaign event at an Indian restaurant in Queens.

Sanders hit back at a rally in the upstate New York city of Binghamton, rallying supporters with a lengthy rift slamming Clinton for promoting fracking as secretary of state and only offering conditional opposition to the practice. The oil and gas drilling method, reviled by environmentalists, has been banned in the state.

Early in the event, Sanders’ crowd booed loudly when he said Clinton’s name.

The harsher tone comes just days before they will meet on stage for the first Democratic primary debate in more than a month. Since their last faceoff, the contest has taken a decidedly negative turn, with the two candidates trading a series of barbs over their qualifications for the White House.

Clinton has avoided directly calling for Sanders to exit the race, saying she’s campaigned until the end in 2008 and that she’s all for a “good hard contest.” But she denounced the aggressive tone that some of his supporters have taken toward her, saying she’d seen reports that her backers have been targeted and harassed.

“There seems to be a growing level of anxiety in that campaign, which I hope doesn’t spill over into the way that his supporters treat other people,” she said.

The April 19 primary in New York has become a make-or-break moment for both the campaigns, with Clinton seeking to avoid the political blow of losing the state she represented for eight years in the Senate. Sanders is hoping to turn a streak of wins into momentum to cut into Clinton’s more than 200 pledged delegate lead.

Clinton’s campaign is pushing for big wins in New York and across the northeast, in an effort to gain what they’ve termed an “all but insurmountable” lead in the delegate race. Should Clinton capture the nomination, she will have to unite the party behind her candidacy — a challenge that could be made more difficult if she targets him with tough attacks.

Sanders believes he can win the state — or at least come close — with a coalition of economically struggling voters upstate and liberals in New York City.

He needs to win 68 percent of the remaining delegates and uncommitted superdelegates if he hopes to clinch the Democratic nomination. That would require blow-out victories by Sanders in upcoming big states and small, including the New York primary.

His aides say he plans to stay in the race until the party convention in July.

Meanwhile, Republican front-runner Donald Trump echoed Sanders’ claims that the system is “rigged,” erupting on Fox News over his loss of recently-allocated delegates in Colorado to rival Ted Cruz.

“I’ve gotten millions more votes, not just a couple, millions of more votes than Cruz,” Trump declared Monday on Fox & Friends when asked if he views the system as unfair. “And I’ve gotten hundreds of delegates more and we keep fighting, fighting, fighting.”

Cruz completed his sweep of Colorado’s 34 delegates last weekend by locking up the remaining 13 at the party’s state convention in Colorado Springs. He already had collected 21 delegates and visited the state to try to pad his numbers there.

“I see it with Bernie too,” Trump said, pointing to the Democratic race. “Every time I turn on your show – Bernie wins, Bernie wins, Bernie wins. and yet Bernie’s not winning. I mean, it’s a rigged system folks.”

Cruz spent Monday campaigning in southern California, a state that holds presidential primaries for both parties on June 7, the last day of primary voting. The Texas senator’s appearance was a reminder that regardless of what happens in New York’s primary, the presidential nomination on the Republican side — if not for both parties — won’t be decided for another two months.

Cruz was scheduled to appear at a rally in Orange County, a Republican stronghold south of Los Angeles, before an evening appearance in San Diego.

The Texas senator has cast himself as more electable than Republican rival Trump, in part because of organizational advantages in the complicated and tedious process of collecting delegates heading into the summer national convention.

(AP)