Sen. Ruben Diaz Sr. is continuing to play his role of chief amigo defender and general thorn in the side of Senate Democratic leadership to the hilt, issuing a statement last night calling for an investigation of the man with the “self-righteous cowboy act who went after Hiram Monserrate.”

That, of course, would be Sen. Eric Schneiderman, who headed up the committee that successfully pushed for Monserrate’s expulsion in February.

“Why has there been no arrest in this crime committed by Senator Eric Schneiderman’s driver?” Diaz Sr. demanded.

“If I were to permit my staff person to commit a hit-and-run or, better yet, if Senator Pedro Espada had permitted his staff person to leave the scene of a car accident, would neither of us be arrested?”

“Will Eric Schneiderman come forward and answer the following questions that would be posed to any DWB who just crashed their car into a parked car: ‘When was the last time you had anything to drink and were you taking any drugs?’

“Or was this situation much simpler to understand: the Senator was just in a hurry and didn’t want his staff member to delay him by stopping?”

(DWB = driving-while-black, FYI).

Diaz Sr. goes on to cite the law on this, which states that anyone involved in an accident in which property damage occurs and the driver of the damaged car is not present is supposed to report to the nearest police station or judicial officer. The penalty for failing to do so is $250 and/or imprisonment of up to 15 days.

“I call upon my colleagues in the New York State Senate to immediately form a Committee and investigate Senator Eric Schneiderman’s criminal activity of flagrantly authorizing, endorsing or encouraging his staffer to leave the scene of an accident,” Diaz Sr. said.

“I call upon Charlie King and Andrew Cuomo to start the process to remove Eric Schneiderman from the Democratic Party. It is a shame that the Democrats could rally behind someone who has such a flagrant disregard for the law.”

“Senator Schneiderman can no longer fool us with his self-righteous cowboy act who went after Hiram Monserrate. He’s not Mr. Clean – he’s Mr. Slick!”

So, I’m choosing to take this statement with a generous shake of salt, because I suspect Diaz Sr. doesn’t really believe Schneiderman should be ousted from the Democratic Party and/or investigated for what the Bronx Democratic lawmaker calls “a flagrant disregard for the law.”

(Then again, we are talking about Ruben Diaz Sr. here, so anything’s possible).

Say what you will about the senator, but he is a savvy guy. And if his aim here is to highlight the hypocrisy that is too often at play in the Capitol – and the Senate, in particular – then the point is well taken.

However, let’s recall that Monserrate was convicted of assaulting his girlfriend. Yes, on a misdemeanor charge, which technically did not merit his expulsion – at least not under a strict reading of the law.

And Espada, though he has not been convicted or even indicted, has been accused of some pretty serious illegal activity by AG Andrew Cuomo.

Again, however, mere allegations of criminal activity – and even subsequent indictments – have not stopped both Democrats AND Republicans from supporting their colleagues in the past. (Ex-Sens. Efrain Gonzalez and Guy Velella come immediately to mind, but I’m sure there are more).