No matter the criticisms directed his way by Republicans, Robert Mueller should count himself lucky: He’s not Ken Starr.

The punctilious, mild-mannered independent counsel appointed by a three-judge panel in the 1990s, Starr investigated all manner of Bill Clinton scandals, most spectacularly the Monica Lewinsky affair.

A former DC circuit judge and US solicitor general in the first Bush administration, he’d struck no one prior to his appointment as a goose-stepping lieutenant in the sex police, or a partisan fanatic likely to be driven by sheer hatred to destroy a Democratic president.

Starr became all of these things for Clinton’s defenders, who thought a good offense was the best defense of a president caught lying under oath.

A former Clinton adviser said his investigation “smacks of Gestapo” and “outstrips McCarthyism.” The estimable historian Garry Wills mused that it shouldn’t be Clinton, but Ken Starr who should be impeached. Anthony Lewis, a liberal lion at The New York Times, opined that Starr’s “abuses were driven by an obsessive — and, for a prosecutor, entirely inappropriate — determination to force President Clinton from office by any means available.”

On and on it went. It was trench warfare over Starr’s every move. In a signature piece of writing during the Lewinsky scandal, Times columnist Maureen Dowd managed to portray Starr, not Clinton, as the sex-obsessed goat, even though the former judge wasn’t the one chasing interns around his desk.

This history is relevant because it shows the forgetfulness of Trump’s critics, who seem to believe that it’s unprecedented for a special counsel to attract the ire of a president’s defenders. In an often abnormal time, the most normal thing that’s happened over the last six months is that attitudes toward the Mueller investigation have broken down along partisan lines.

Mueller may be motivated by a disinterested pursuit of the truth (tempered, one hopes, by an appropriate sense of limits), but his most ardent fans are rooting for any criminal infraction that, in their fevered dreams, will lead to President Trump getting frog-marched from the White House.

The persistent fantasy that Trump can somehow be leveraged from office is behind the push to criminalize any blameworthy conduct on his part or that of his associates.

It wasn’t just bad form in pursuit of a foolish policy for incoming national-security adviser Michael Flynn to talk to Russian ambassador Sergey Kislyak about sanctions; it was a violation of the Logan Act.

Don Jr.’s notorious meeting with Russians wasn’t just amateurish and ill-considered; it was a violation of a law against taking an in-kind contribution from a foreign national.

The continued operation of Trump businesses isn’t just unseemly; it’s a violation of the Emoluments Clause.

Trump’s withdrawn directive to fire Mueller wasn’t merely a potentially catastrophic decision that he got talked out of; it was evidence of obstruction of justice.

Very little can’t be made to fit under this rubric. In his rebuttal to the Nunes memo, New York Democrat Jerry Nadler alleged that the document made Republicans an accessory to a crime — “part and parcel” of Trump’s effort “to obstruct the Special Counsel’s investigation.”

Even in the worst case for Trump, Mueller is unlikely to charge him with a crime. There is longstanding Office of Legal Counsel guidance that it’s unconstitutional to indict a president while he’s in office. The worst case for Trump is probably a report by Mueller that could become, in effect, an impeachment referral.

Much will depend on the facts; on whether Mueller is willing to stand aside if he doesn’t find anything to justify his continued investigation; and on who wins Congress this year — and, if the Democrats, by how much. But there can be little doubt that, in their hearts, most Democrats have decided for impeachment. The fighting now may be mere skirmishing compared to the larger political war to come.

Twitter: @RichLowry