President Trump accompanied Federal Reserve Chairman Jerome Powell on a tour of the Fed's headquarters renovation last summer. The Justice Department is investigating cost overruns on the project. Chip Somodevilla/Getty Images hide caption toggle caption Chip Somodevilla/Getty Images President Trump has once again threatened to fire Federal Reserve Chairman Jerome Powell, whose term is set to expire in a month. Trump also vowed to continue a criminal investigation of the central bank, which could complicate the path of installing Trump's nominee to replace Powell. The president's threat came in an interview with Fox Business that aired on Wednesday. "He's doing a bad job," Trump said of Powell. "He should be lowering interest rates." Trump has repeatedly threatened to remove the Fed chairman, although it's not clear he has the authority to do so, absent a showing of serious wrongdoing.…