Democratic presidential candidate Michael Bloomberg responded to criticism from Massachusetts Senator Elizabeth Warren and other rivals that he’s trying to buy the election by self-financing his campaign, saying they had the same opportunity in life to build up a fortune as he did.

The former New York mayor said in an interview on “CBS This Morning” that he didn’t come from a wealthy family and earned his money by building up his business. He said his rivals, too, “had a chance to go out and make a lot of money.”

“I’m doing exactly the same thing they’re doing, except that I am using my own money,” Bloomberg said. “They’re using somebody else’s money and those other people expect something from them. Nobody gives you money if they don’t expect something. I don’t want to be bought.”

Bloomberg is the founder and majority owner of Bloomberg LP, the parent company of Bloomberg News.

The former New York mayor said he intends to entirely self-fund his campaign and has already booked more than $64 million in television ads since announcing his candidacy on Nov. 24, according to Advertising Analytics, which tracks political commercials.

Bloomberg also defended the company’s policy of not investigating him or other Democrats while continuing to investigate President Donald Trump, saying that Bloomberg News carries coverage from many top news outlets so those kinds of stories are available to its readers.

“People have said to me, ‘How can you investigate yourself?”’ he said on CBS. “And I said, ‘I don’t think you can.’"

He also said in response to concerns that Bloomberg journalists can’t investigate Democrats by saying, “They get a paycheck, but with your paycheck comes some restrictions and responsibilities.”

This article was provided by Bloomberg News.