Sen. Thom Tillis (R-N.C.) on Sunday said that he would no longer block Kevin Warsh 's Federal Reserve chair confirmation, removing a key hurdle for President Trump 's pick to lead the central bank. Why it matters : The DOJ said last week that it was dropping its investigation into current Fed chair Jerome Powell, satisfying the key Republican's conditions for supporting Warsh. What they're saying : "I have been clear from the start: the U.S. Attorney's Office criminal investigation into Chair Powell was a serious threat to the Fed's independence, and it needed to end before I could support Kevin Warsh's confirmation," Tillis said in a Sunday statement. Though the probe into Powell has ended, the Department of Justice is allowing the Fed's watchdog to investigate cost "overruns" related to its multi-billion dollar building renovation project.…