Assembly Speaker Sheldon Silver yesterday raised the stakes in the rapidly growing Aqueduct scandal, formally calling on state Inspector General Joseph Fisch to launch an immediate investigation of the mess.

Good for him.

In fact, we can't think of anyone more appropriate to conduct a thorough, independent and expeditious review of the entire bidding process, which led up to Gov. Paterson's dubious selection of Aqueduct Entertainment Group for the lucrative racino contract.

Fisch, to put it mildly, is a straight shooter -- one of the very few left in the ethical cesspool that is New York's state capital. In his short time in office, he and his team have already managed to uncover more malfeasance than just about any other investigators.

Now Silver has asked him to determine, essentially, how AEG managed to land the Aqueduct contract. Moreover, he wants an investigation into all of the procedures the state Lottery Division used in evaluating each of the prospective bidders and to determine whether the agency, and others involved in the process, followed the law.

Again, if anyone can get to the bottom of this mess, it's Fisch.

But we'd like to see Silver go one step further: The speaker needs to make it clear that if Fisch declines to step in, he will kill the AEG deal.

Bang. Just like that.

Silver has the power.

He needs to exercise it.

The nonsense needs to end.