Buoyed Tuesday night by his decisive victory in Wisconsin, Bernie Sanders insisted that he had a path to the Democratic nomination, one that goes straight through New York.
"Do not tell Secretary Clinton — she's getting a little nervous, and I don't want her to get more nervous — but I believe we've got an excellent chance to win New York," he told a crowd of supporters.
On Wednesday, Hillary Clinton moved aggressively to try to block that path, questioning Sanders' readiness to be president and his Democratic bona fides, even as her allies attacked his opposition to some gun control measures and other groups went after his positions on the Middle East.
Sanders responded in kind, saying of Clinton that "I don't believe that she is qualified" to be president because of her vote for the Iraq war and the contributions her political operation has taken from Wall Street firms, among other reasons. A spokesman for Clinton called the comment "a new low."
It was, in short, opening day for the sort of no-holds-barred battle that New York voters have come to expect in a state that could prove decisive in the prolonged Democratic nomination battle.
Weeks have passed since Clinton and Sanders aggressively fought on the same terrain. Each has tried to pick off favorable locales in which to drive up delegate counts. But New York is a state that neither can afford to lose.
Clinton retains a large lead in the number of delegates to the Democratic convention in July. If she wins New York, where she currently leads in polls, her margin over Sanders, already formidable, would be close to insurmountable.
But if Sanders can upset Clinton here, in a state that she represented in the Senate and calls home, his Tuesday night assertion of an open path would suddenly seem achievable.
That reality led Clinton to once again begin directly criticizing her Democratic rival after weeks of trying to ignore him in favor of campaigning against Donald Trump, the Republican front-runner.
During a television interview from her home in Chappaqua, N.Y., she suggested that Sanders' answers — or lack thereof — to substantive questions in a New York Daily News interview had "raised a lot of serious questions" about his ability to follow through on his campaign promises.
"You can't really help people if you don't know how to do what you are campaigning on," she said, adding that Sanders "hadn't done his homework."
Later, in a speech to a union gathering in Philadelphia, where voters will cast ballots a week after New York, she said of Sanders that "in a number of important areas he doesn't have a plan at all."
"We need a president who doesn't just complain about trade. We need a president who knows how to compete against the rest of the world and win," she said.
Having questioned Sanders' competence in one interview, Clinton attacked his partisan bona fides in another.
"He's a relatively new Democrat, and, in fact, I'm not even sure he is one," she said in an interview with Politico, referring to Sanders' many years as an independent. "So I don't know quite how to characterize him."
Egging on both candidates as they strike at each other will be New York City's rambunctious media, which has a way of throwing sparks onto political kindling. Both candidates have already gotten singed.
During the days-long argument over scheduling another debate between the candidates, the New York Daily News ran a giant front-page headline blaring, "Don't be a bum, Hil!"
On Wednesday, the same newspaper highlighted Sanders' opposition to lawsuits filed by victims of gun violence against firearm manufacturers, with a headline declaring, "Bernie's Sandy Hook shame," a reference to the 2012 massacre at a Connecticut elementary school.
Although Sanders has publicly said that his path to the nomination is "narrow," he hasn't shrunk from the fight. He's highlighted the hundreds of thousands of dollars Clinton has earned by giving Wall Street speeches and accused her of supporting trade deals that have cost American jobs.
His supporters have gone further. The actress Rosario Dawson, for example, recently called attention to the FBI's investigation into the private email server that Clinton used while secretary of State, a subject Sanders has eschewed.
Clinton, who wanted by now to be uniting the party for a general election battle against Republicans, has become increasingly agitated with Sanders.
"They're getting more negative," she told Politico. "I think there is a persistent, organized effort to misrepresent my record, and I don't appreciate that."
And now Clinton's surrogates in the party are joining her in taking a more aggressive tone.
In a conference call with reporters, former New York Rep. Carolyn McCarthy, whose husband was killed in a mass shooting on a New York commuter railroad, said Sanders had "never been there for the people that have been extremely hurt."
"I am less sure than ever before whether Sen. Sanders is with us," added Sen. Christopher S. Murphy of Connecticut, who has been an outspoken critic of the National Rifle Assn. since the Sandy Hook massacre.
"It is not easy for me to speak up against a colleague, someone I sit next to in the U.S. Senate," he added. But, he said, "this issue is too important for me to remain silent."
Meantime, the Anti-Defamation League demanded that Sanders publicly correct a statement he made in the Daily News interview in which he exaggerated the number of civilians killed during Israel's 2014 war in the Gaza Strip. Sanders had estimated the civilian death toll at more than 10,000, which is roughly five times more than the United Nations and Palestinian organizations claim.
Sanders was born and raised in Brooklyn, and still talks — or tawks, as the case may be — like a New Yorker, but Clinton is the one with political experience in the state, having moved to New York as first lady to launch her own political career, ultimately winning two statewide campaigns for the U.S. Senate, where she represented the state from 2001 to 2009.
Stu Loeser, a Democratic political operative who was spokesman for former New York Mayor Michael R. Bloomberg, said her experience with the New York media would be a major asset in the weeks ahead.
"Not everyone who comes into the New York media market having won a couple dozen primaries and caucuses is prepared for the ferocity of the media here," he said. "Her 2000 campaign began with extreme skepticism" on the part of reporters. "And she's won them over. She knows what she's doing."
Sanders has some significant assets of his own, however: money and grass-roots enthusiasm.
He greatly outspent Clinton in Wisconsin, and in New York, he's deploying the tens of millions of dollars he's raised from his legion of small donors — $44 million in March, to Clinton's $29 million — to poke at her vulnerabilities.
The New York chapter of Working Families, a leftist group that has endorsed him, says it already has seen a major response to its organizing efforts for Sanders.
"There's no question this is going to be an intense battle for New York," said Bill Lipton, the group's state director. "Both sides realize this is an important contest.
"We're going to be pulling out all the stops," he added.
Phil Singer, a Democratic strategist who has advised New York Gov. Andrew Cuomo and worked on Clinton's 2008 campaign, said the pressure is on Sanders to show viability.
"He's likely to sharpen his message. I think he's forced to," he said.
Even then, though, Clinton's lead in delegates remains so large that Sanders may not be able to overcome it, he added.
"The reality of the various electoral dynamics can be somewhat divorced from the street fight that will take place," he said. "They could have a knock-down, drag-out fight. But it may not have a material effect on the outcome."
Memoli reported from New York and Megerian from Milwaukee. Times staff writer Evan Halper in Washington contributed to this report.