In an escalating a war of words between Democratic rivals, Bernie Sanders says Hillary Clinton is not “qualified” to be president.

“Secretary Clinton appears to be getting a little bit nervous,” Sanders said at a rally in Philadelphia on Wednesday. “And she has been saying lately that she thinks that I am ‘not qualified’ to be president. Well, let me, let me just say in response to Secretary Clinton: I don’t believe that she is qualified.”

The Vermont senator cited the former secretary of state’s voting record in the Senate and her ties to Wall Street as reasons she should be disqualified from consideration for the nation’s top job.

“I don’t think that you are qualified if you get $15 million from Wall Street through your super-PAC,” Sanders said. “I don’t think you are qualified if you voted for the disastrous war in Iraq. I don’t think you’re qualified if you supported almost every disastrous trade agreement.“

He added: “I don’t think you are qualified if you supported the Panama free trade agreement, something I very strongly opposed, which … gave the green light to wealthy people and corporations all over the world to avoid paying taxes owed to their countries.”

Sanders’ comments came in response to a pair of interviews in which Clinton questioned whether he is qualified to be president — and whether an independent senator and self-described democratic socialist is even a true Democrat.

“He’s a relatively new Democrat, and, in fact, I’m not even sure he is one,” Clinton said in a podcast interview with Politico published Wednesday. “He’s running as one. So I don’t know quite how to characterize him.”

Sanders has previously sought and won office only as an independent, remaining formally outside the Democratic party from the start of his political career as mayor of Burlington, Vt., in 1980 until the start of his bid for the Democratic presidential nomination in 2015.

On MSNBC’s "Morning Joe” Wednesday morning, Clinton was asked whether Sanders’ answers about his plan to break up big banks during a well-scrutinized interview with the New York Daily News were disqualifying.

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“Well, I think he hadn’t done his homework, and he’d been talking for more than a year about doing things that he obviously hadn’t really studied or understood,” Clinton said. “And that does raise a lot of questions.”

“I think the presidents who are successful know what they want to do and they know how to do it,” Clinton said later on CNN. “And they hit the ground running, able to do every aspect of the job both as president and as commander in chief.”

The Clinton campaign fired back, insisting their candidate never said Sanders was not qualified to be president.

“Hillary Clinton did not say Bernie Sanders was 'not qualified,’” Brian Fallon, press secretary for the Clinton campaign, wrote on Twitter. “But he has now — absurdly — said it about her. This is a new low.”

“Bernie Sanders, take back your words about Hillary Clinton,” Fallon added on Twitter along with the hashtag “#TakeItBackBernie.”

In response, Sanders’ supporters have taken to Twitter to mock the Democratic frontrunner with their own hashtag: “#HillarySoQualified.”

The back and forth over presidential qualifications comes ahead of New York’s Democratic primary on April 19, a crucial contest that Clinton hopes to win in her adopted home state to stem Sanders’ momentum. The Vermont senator has won six of the last seven primaries and caucuses.

“It’s kind of a silly thing to say,” Clinton said on Thursday when asked about Sanders’ remarks. “I don’t know why he’s saying that.”

