The good news is, that President lost.
George Bush publicly declared Tom DeLay innocent of charges.
Of course, this is not only wrong, and perhaps criminal on its own merits, but it exposed Bush's own hypocrisy, as he'd been so steadfast in other instances to not comment on, say, the Fitzgerald probe. Watch Scotty catch righteous hell for the double-standard here. See also here and here.
I haven't read much more of the discussion, but as I said in comments to this post, a President Behaving Badly has done this sort of thing before. I haven't seen the historical precedent otherwise mentioned in any of these discussions*.
It's not taught that Thomas Jefferson was in many ways a terrible President, who effectively nullified everything he'd previously (and afterward) believed in. But he was, and he did.
Thomas Jefferson tried to railroad his ex-Vice President, Aaron Burr. Because he had a personal vendetta against Burr, Jefferson tended to involve himself into the proceedings. He publicly announced Burr's guilt, before the trial took place, just as Bush has publicly declared DeLay's innocence. Here is a fairly long but illuminating passage from Leonard Levy's Jefferson and Civil Liberties: The Darker Side:
In the closing years of his presidency, the Burr conspiracy and the embargo fixed Jefferson's attention. On both subjects he was insensible to constitutional limitations and to standards of fairness. Had Timothy Pickering masterminded the Administration's conduct of the Burr case, it would not have been remarkable. But Thomas Jefferson was responsible. The President of the United States, in a special message to Congress, gave the nation to understand that a citizen who just a few weeks earlier had been exonerated by a federal grand jury was guilty of high treason. On the basis of "little" that constitututed "formal and legal evidence," chiefly letters "often containing such a mixture of rumors, conjectures, and suspicions, as render it difficult to sift out the real facts," Jefferson announced that Burr, at the head of a military enterprise, "had sought the severance of the Union." He had planned to seize New Orleans, plunder its wealth and military supplies, use it to detach the West beyond the Alleghenies, and conquer Mexico. Burr's guilt, concluded Jefferson, "is placed beyond all question." Whether Burr's criminal enterprise was a filibuster against the territory of a friendly nation, or treason against the United States, or conspiracy to commit treason, is quite beside the point. John Adams made the point simply enough: "But if Burr's guilt is as clear as the Noon day Sun, the first Magistrate ought not to have pronounced it so before a Jury had tryed him."
Having convicted Burr before the bar of public opinion prior to his apprehension, the first Magistrate proceeded relentlessly to mobilize executive resources to prove the preconcieved guilt...
The object was not to secure justice by having Burr's guilt -- or innocence -- fairly determined, but to secure a conviction, no matter how, on the charge of high treason...
Of course, this is the only way Bush compares to Jefferson (though Christopher Hitchens has a fantasy to the contrary), and here was Jefferson at his absolute worst. Bush has declared DeLay innocent, Jefferson declared Burr guilty; Jefferson lost his case and his cause, let's hope Bush's fate is the same.
*Edit: I missed it the first time. Dwight Meredith recalls a different example.