* Federal Reserve Chair Jerome Powell now heads into his next challenge: a potential threat that President Donald Trump could undermine his authority by soon naming his pick to head the central bank. * In the wake of the intense criticism, Wall Street has been buzzing over the potential for a “shadow chair,” or someone Trump could install as a central bank gadfly until Powell’s term expires. * A report indicated that Trump is considering naming the successor sooner than expected in an attempt to influence interest rate policy.