Elizabeth Warren, the presidential candidate who has campaigned on breaking up Silicon Valley giants, says conflicts of interest should keep the Trump administration’s antitrust enforcement chief from overseeing a Justice Department investigation of Google and Apple.

Makan Delrahim, who heads the agency division overseeing the investigations, was paid to lobby for approval of Google’s $3.1 billion takeover of online advertising firm DoubleClick in 2007, Warren wrote in a letter to Delrahim and ethics officials at the Justice Department. Not only did Delrahim earn $100,000 from Google that year, he was paid by Apple in 2006 and 2007 to lobby the George W. Bush administration on patent-reform issues, she said.