It’s the biggest political purge since Richard Nixon’s Saturday Night Massacre. And Alberto Gonzales is the worst attorney general since Nixon’s John Mitchell.

Make no mistake about it. We know from e-mails exchanged between then-White House Counsel Harriet Miers and Gonzales Chief of Staff Kyle Sampson: The summary firing of eight U.S. attorneys, without cause, was orchestrated at the highest levels of the White House and the Justice Department — for purely political reasons.

Miers originally wanted to fire all 93 U.S. attorneys. Gonzales demurred. So she and Sampson then put together a “target list” of those about whom they’d received complaints — for being too tough on Republicans or not tough enough on Democrats. And, Sampson warned, once the stuff hit the fan, they had to “Prepare to Withstand Political Upheaval.” Of course, once the stuff did hit the fan, Sampson resigned.

But that shouldn’t let Gonzales off the hook. On Jan. 18, he’s the one who promised the Senate Judiciary Committee he would never appoint a U.S. attorney without seeking Senate confirmation. Yet at the same time, we now know from Sampson’s e-mails, Gonzales was planning to use new powers of the Patriot Act to do just that.

Republicans argue that U.S. attorneys serve at the pleasure of the president, so this is no big deal. Nonsense. True, they are political appointees, but, once in office, they should not be fired simply because they refuse to do the president’s political bidding.

This is one more strike against Alberto Gonzales: the NSA spying scandal; FBI abuses of the Patriot Act; rendition and torture; and now sacking U.S. attorneys without cause. How many more strikes goes he get?

It’s time for Gonzales to resign — or be fired.