U.S. Federal Election Commission Commissioner Ellen Weintraub testifies on Capitol Hill in Washington, Wednesday, May 22, 2019.Carolyn Kaster | APThe head of the Federal Election Commission subtweeted President Donald Trump on Thursday after the president called on China to investigate his potential 2020 rival Joe Biden and his son Hunter.In a post on Twitter, chair Ellen Weintraub resurfaced a June memorandum stating that it is illegal for anyone running for public office to solicit help from a foreign national.Weintraub had originally drafted the memorandum over the summer after the president told ABC News that he may not alert the FBI if a foreign government offered dirt on a 2020 rival.Weintraub, a Democrat, has served on the commission since 2002 and was appointed by George W. Bush. The FEC is independent and bipartisan by law. Tom Moore, Weintraub’s counsel, told CNBC in a text message that Weintraub “will let the Tweet speak for itself.””I would not have thought that I needed to say this,” Weintraub wrote in June.On Thursday, she re-upped the message and included an image of a microphone. She wrote: “Is this thing on?” She did not name Trump in the memorandum or in either tweet.Weintraub’s tweet came after the president said on the White House South Lawn that China “should start an investigation into the Bidens, because what happened in China is just about as bad as what happened with Ukraine.”In the memorandum, Weintraub wrote that she wanted to “make something 100% clear to the American public and anyone running for public office.””It is illegal for any person to solicit, accept, or receive anything of value from a foreign national in connection with a U.S. election,” she wrote, citing federal election law.A representative of the Trump reelection campaign did not immediately respond to a request for comment. In a statement earlier in the day, the Biden campaign called the president’s comments “a grotesque choice of lies over truth and self over the country.”Despite Weintraub’s harsh, if veiled, words, the FEC is currently unable to take any official enforcement actions. Four votes are required for the commission to take action. The commission has had only three members since vice chairman Matthew Petersen resigned in August. Commissioners are appointed by the president and confirmed by the Senate.