The race between Democratic candidates Bernie Sanders and Hillary Clinton is growing increasingly contentious ahead of the New York primary on April 19. During a rally in Pennsylvania Wednesday, Bernie Sanders responded to Hillary Clinton’s claims that he is not qualified to be president by saying that she is the one who is “not qualified.”

Sen. Bernie Sanders: “Well, let me—let me just say in response to Secretary Clinton, I don’t believe that she is qualified if she is—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.”

Also speaking in Pennsylvania on Wednesday, Hillary Clinton fired back at Sanders, saying his ideas are flawed because his numbers “don’t add up.”

Hillary Clinton: “But Senator Sanders and I have some real differences about how we would go about achieving our goals as president. And like a lot of people, I am concerned that some of his ideas just won’t work, because the numbers don’t add up.”