That would be the dread Kanjorski amendment, which created a real uproar when the Pennsylvania congressman first announced it two weeks ago. According to Politico's Victoria McGrane, the measure isn't as hawkish as a lot of bank lobbyists feared at the time--for example, it doesn't lay out a set of criteria according to which the government would automatically break up large, interconnected firms. But it does shift the discretion to break up big banks from the Fed (which is generally less hawkish on these matters) to the proposed council of regulators, which is likely to be a bit more skeptical of them (particularly the FDIC, which will have a seat on the council).
On the other hand, we don't know what the council protocol will be. If, for example, each member gets a veto over this kind of thing, then the council is obviously only as hawkish as its least hawkish member...