Whatever happened to Bush’s brain? No, this isn’t some lame joke for BBC reporters. It’s a question about the ideological rudder of George W Bush’s presidency, Karl Rove. It was Rove who crafted the new Republican majority in America: that of a religiously centred party dedicated to steering the largesse of bigger government to its own faith-based and corporate constituencies.

It was Rove who used the war to marginalise fiscal conservatives alarmed at spending and libertarian conservatives worried about civil liberties. It was Rove who forged a difficult alliance between a growing conservative intelligentsia and evangelical Protestant voters.

It was Rove who decided that a wartime president, rather than seeking national unity, should use the war as a means to drive a wedge into the Democrats and consolidate his own supporters. It was Rove who was the architect of a 51% strategy of playing to the party base, and expanding it, especially among blacks and Latinos, rather than reaching out to the centre.

So how, one wonders, did Rove approve of the nomination of Harriet Miers to the Supreme Court? In one move the president has divided the Republican coalition. Washington’s conservative chattering class has blown its top over what it sees as cronyism, mediocrity and ideological incoherence. For that matter, how did Rove let Bush appear so feckless during the Katrina fiasco?

Bush’s approval rating among African-Americans is now, in one poll, at 2%. Bush’s remaining loyalists are now at war with each other — and we have a month before Miers faces the Senate committee. Whatever else this is, it isn’t political finesse.

There are two plausible interpretations for Rove presiding over such a mess; but they’re not mutually exclusive. The first is that Rove has never been as good a political tactician as his enemies fear he is. Rove’s signature contributions during the election — using gay marriage as a wedge issue and helping raise questions about John Kerry’s war record — might have made a difference in a state or two, but they were more like student-politician dirty tricks than a brilliant long-term strategy.

The decision to junk fiscal discipline and let the Republicans feed even more voraciously than Democrats at the government trough is also beginning to look a little less shrewd in retrospect.

Rove’s key strategic decision after the last election to spend all of Bush’s political capital on social security reform was an unmitigated disaster. The reform went nowhere and the president’s ratings continued to sink. The current unravelling should therefore be seen as simply an end to Bush’s long run of good luck. And Rove was never that good to start with.

The second explanation is that Rove is distracted. Hanging over Washington is a zealous prosecutor, Patrick Fitzgerald, who has spent months getting to the root of who might have leaked the identity of Valerie Plame, an undercover CIA operative.

The information may well have been released as a way to smear Plame’s husband, Joseph Wilson, who had attacked the credibility of the White House’s case for war against Saddam Hussein. The tactic smells of Rove — and it also happens to be against the law.

Rove has now appeared before a grand jury several times. The prosecutor is no wimp. He has already sent a journalist at The New York Times to jail for refusing to disclose sources. The scope of his investigation suggests it might involve more than just a single, perhaps unwitting, crime. It might get into the core of the group that sold the country on the Iraq war. It’s enough to give Rove the jitters — even if, as is still quite possible, he is cleared of wrongdoing.

Worse: Rove’s two key allies in Washington are also in trouble. The man who controls the small Republican majority in the House of Representatives, Tom DeLay, has just been indicted twice for allegedly evading Texas campaign finance laws and “money-laundering” campaign donations. He received a nasty subpoena for phone records and other information last week, and has had to quit his post just while his president is on the skids. Last Thursday the Senate majority leader, Bill Frist, was also subpoenaed by the Securities and Exchange Commission and ordered to hand over documents related to charges of insider trading.

Could Bush survive without Rove? Once unthinkable, Washington’s chatterers now talk of it incessantly. If leaders of the religious right in the Senate, such as Sam Brownback of Kansas and George Allen of Virginia, vote against Miers, it will put Rove in a spot.

For the record, Rove told one of his mouthpieces in the media last week that he was “not merely enthusiastic, but adamant and even vehement” in support of the nomination of Miers. It’s also true that many second-term presidents have been this unpopular before, some of them more so, and also mired in scandal. The president’s position, in other words, is far from unprecedented. But that makes Rove’s inability to staunch the post-Katrina, post-Miers bleeding on the Republican right all the more striking.

Which leads to a third possibility. Is Bush quietly unmooring himself from Rove and Rove from Bush? The Miers pick, in particular, does not strike me as a Rove-like decision. It smacks much more of the Bush family’s exercise of its own dynastic prerogatives.

Muddying the waters further, an anonymous Republican source told The Washington Post on Friday: “My sense is Karl knows he has spent a lot of political capital with the president on this CIA leak case. No matter how close Karl is to the president, there is a limit to how much capital you can spend even with a close, close friend.”

Translation: don’t blame Karl for Harriet.

That sounds like distancing to me. If Rove is indicted for an illegal leak, his White House role will be over. If he isn’t indicted, but comes out of the Plame affair with a distinct whiff of sleaze around him, the president will have to choose either to fire him or live with him. That decision may well tell us more about the future of this administration than anything since its re-election. And it may help explain a lot about its recent past as well.

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