I wonder if it's possible that he senses that he might be able to get some other Democratic support for the idea. I mean, now is a really good time to do it. Since this is a situation where members of congress are going to vote in a way that will be very unpopular with their constituents, it may give them a way to try to spin their vote and make peace with their constituents. Like "We had to vote for this but, as a consequence, we now pledge to audit and investigate the Federal Reserve..."