The US Department of Justice has dropped its criminal investigation into Federal Reserve Chairman Jerome Powell regarding alleged cost overruns in building renovations. Instead, the matter will be handled through an internal probe by the central bank's inspector general. The investigation was part of a long-standing feud between Powell and President Donald Trump, who has criticized the $3.1 billion cost of the project and repeatedly attacked Powell for refusing to lower interest rates. The decision to drop the probe comes as the Trump administration seeks to secure the Senate confirmation of Kevin Warsh to succeed Powell. Key Republican Senator Thom Tillis had previously withheld support for Warsh unless the investigation into Powell was ended. Powell, whose term ends on May 15, has maintained that the pressure was an attempt to undermine the Fed's independence.