Arlen Specter, the Pennsylvania Republican who is due to assume the chairmanship of the Senate Judiciary Committee, is in the middle of a contrition tour this week. It’s a humbling ritual, peculiar to public figures, by which a politician or some other celebrity abases himself before a powerful and pitiless constituency that he has inadvertently offended.

Contrition tours are always fun to watch, but several factors make Mr. Specter’s richer than most.

For one thing, the stakes are unusually high: Mr. Specter’s fate will set the tone for much of what happens in the Republican Congress during President Bush’s second term. For another, Mr. Specter is not a man to whom contrition comes easily. And to top it off, it is unclear what he is supposed to be contrite about, precisely.

The immediate cause of the imbroglio came the day after Election Day, when The Associated Press reported that Mr. Specter had “bluntly warned [Mr. Bush] against putting forth Supreme Court nominees who would seek to overturn abortion rights or are otherwise too conservative to win confirmation.”

If indeed this was a warning, it was an odd one. As Judiciary chairman, Mr. Specter would serve as point man in getting Mr. Bush’s nominees approved by the Senate. He himself, in other words, would play a decisive role in determining which nominees were “too conservative” to be confirmed.

Republican loyalists have never much liked Specter, who survived a dicey conservative challenge in his primary last April. Of 51 Republican senators in 2003, Congressional Quarterly rated Mr. Specter 48th in supporting Mr. Bush’s positions. Among Judiciary Committee Republicans, who will decide whether to name him chairman when the new Congress convenes in January, his rankings by various interest groups tag him as the most left-leaning, by a long stretch.

Within hours of The Associated Press story, conservative activists in Washington did what they had wanted to do all along – declare Mr. Specter unfit to assume the chairmanship.

Hence the contrition tour, which Mr. Specter has undertaken in its classic form. The first step always is to blame the press.

“The current controversy was created by incorrect reporting,” Mr. Specter wrote in an op-ed in the Wall Street Journal last week. “I never ‘warned’ the president on anything – and especially not that I’d block pro-life nominees.”

Instead, Mr. Specter said, he was merely making a disinterested political observation, pundit-like: that Democrats are likely to filibuster pro-life nominees, as they did in the last session of Congress.

The next step in a contrition tour is to round up allies, the unlikelier the better. To support his allegation that he was misquoted, Mr. Specter cited not only a reporter from Fox News but also Rush Limbaugh – the equivalent, for many conservative activists, of quoting scripture.

Mr. Specter, who once excoriated religious conservatives as the “radical fringe,” even cited the Reverend Pat Robertson in self-defense: “I am not worried about Arlen Specter, and I think he’ll be fine,” saith Mr. Robertson.

So far, however, the tour seems not to be working. Senate Majority Leader Bill Frist this weekend declined to issue a ringing endorsement of Mr. Specter’s chairmanship, and his apparent indifference to Mr. Specter’s fate is a potentially lethal blow. Conservative activists, meanwhile, remain unappeased, raising the growing possibility that they will make opposition to Mr. Specter’s chairmanship their own “litmus test.”

Though press reports cast the Specter controversy as a battle between the religious right and moderate Republicans, the conservative brief against Mr. Specter goes beyond his support for abortion rights and his past opposition to some pro-life nominees.

Two groups leading the charge against him – the Club for Growth and the National Taxpayers Union – take no official position on abortion rights. Instead, they cite Mr. Specter’s opposition to the first Bush tax cut in 2003 and his coziness with trial lawyers, which inspired him to lead the fight against tort reform.

If Mr. Specter is deemed an unacceptable heretic by activists across the party’s right flank, social and fiscal conservatives alike, it’s very bad news for him – but also for any Republicans who hope to forge a governing majority from the large electoral success of 2004. When asked last week why he was opposing Specter, the president of the Club for Growth, Steve Moore, said: “Arlen Specter is the last of a dying breed of northeastern liberal Republicans,” as though the very existence of such creatures was intolerable. Yet liberal Republicans are still Republicans; you’d think this is one endangered species that Republicans, whatever their ideological coloration, would want to preserve. One reason – perhaps the main reason – the Democratic Party has lately fallen into eclipse has been its rigid enforcement of ideological conformity, which depleted the ranks by driving non-liberal Democrats, moderates, and conservatives elsewhere.

We’ll know by the end of the month whether Mr. Specter’s contrition tour has succeeded. By then we’ll know, too, whether the activists who control the Republican Party will make the same mistake their Democratic counterparts have been making for years.

Mr. Ferguson is a columnist for Bloomberg News.