At a press conference on Thursday, Bernie Sanders doubled down on his searing statement last night that he doesn’t believe Hillary Clinton is “qualified” to be president.

With a backdrop of union workers in Philadelphia, Sanders said, “I have run an issue-oriented campaign. Now, it’s hard, as we can see here. The media’s not particularly interested in about why the middle class declines, in wage and income disparity, that’s not what they’re interested in.”

“We have tried in rally after rally — many of you have been there — to talk about the most important issues facing the American people.

“But if Secretary Clinton thinks just because I’m from the small state of Vermont and we’re going to come here to New York and Pennsylvania and they’re going to beat us up and they’re going to go after us in some kind of really uncalled for way, that we’re not going to fight back, they can guess again because that’s not the case.

“This campaign will fight back, so when you have headlines like the Washington Post, quote, Clinton questions whether Sanders is qualified to be president, my response is, well, if you want to question my qualifications, let me suggest this: then maybe the American people might wonder about your qualifications, Madam Secretary.”

Sanders doubling down comes after his speech to a raucous crowd in Philadelphia Wednesday night, where he declared Hillary Clinton is “not qualified” to be president because of the funds she takes from special interest groups.

MSNBC rushed to air the footage before Sanders’ speech was even over.

“She has been saying lately,” Sanders told a packed basketball area, “that she thinks that I am ‘not qualified’ to be president,” eliciting sustained boos from the audience.

“Well, let me just say, in response to Secretary Clinton, I don’t believe that she is qualified if she is…” he said, before being met with wild cheers. “If she is through her Super PAC taking tens of millions of dollars in special interest funds.

“I don’t think that you are ‘qualified’ if you get $15 million from Wall Street through your Super PAC. I don’t think you are ‘qualified’ if you voted for the disastrous war in Iraq.”

Host Rachel Maddow observed before airing the statement that Sanders was going after Clinton “in a way we’ve not heard before.”

“This is what you call a tipping point. This is when the Democratic presidential primary process suddenly becomes a very different contest with a very different aim from the way it started out,” Maddow said.