A LIBERAL SCALIA IS UNLIKELY…. The last two presidents each got to fill two Supreme Court vacancies, but each approached the process from different directions. Clinton wanted to avoid a bitter fight with Republicans, so he picked jurists who were part of the center-left mainstream, but who were hardly strident ideologues.

Bush didn’t much care about whether senators balked. His goal — the Miers debacle notwithstanding — was to pick young, rigid conservatives, who could be counted on to deliver consistently for the right for decades to come. His party was in the majority, and the threat of a filibuster didn’t faze him.

If recent reports are accurate, President Obama seems to prefer the Clinton approach.

Pamela S. Karlan is a champion of gay rights, criminal defendants’ rights and voting rights. She is considered brilliant, outspoken and, in her own words, “sort of snarky.” To liberal supporters, she is an Antonin Scalia for the left.

But Ms. Karlan does not expect President Obama to appoint her to succeed Justice David H. Souter, who is retiring. “Would I like to be on the Supreme Court?” she asked in graduation remarks a couple of weeks ago at Stanford Law School, where she teaches. “You bet I would. But not enough to have trimmed my sails for half a lifetime.”

While there are clear political advantages to Mr. Obama if the perception is that he has avoided an ideological choice, Ms. Karlan’s absence from his list of finalists has frustrated part of the president’s base, which hungers for a full-throated, unapologetic liberal torchbearer to counter conservatives like Justice Scalia.

It has been more than 40 years since a Democratic president appointed someone who truly excited the left, but Mr. Obama appears to be following President Bill Clinton’s lead in choosing someone with more moderate sensibilities.

Those hoping for a liberal Scalia — and I include myself in this group — should adjust expectations accordingly. Obama isn’t going to nominate a conservative, but by all appearances, the appropriate label will be more “center-left” and less “liberal.”

And that is, in all likelihood, part of the point of an article like this one in the NYT. The White House has been pretty tight-lipped about the search process, but it dished to the Times, probably as part of the larger strategy of shaping perceptions in advance. The signal is obvious — Obama’s pick isn’t one of those wild-eyed liberals; she’s entirely mainstream. As Scott Lemieux noted, “I do suspect … that there’s at least some political positioning going on here, emphasizing the moderation of even pretty liberal picks.”

And who’s on the shortlist? “The president has narrowed his list to four, according to people close to the White House — two federal appeals judges, Sonia Sotomayor of New York and Diane P. Wood of Chicago, and two members of his administration, Solicitor General Elena Kagan and Homeland Security Secretary Janet Napolitano.”

The announcement could come as early as today.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.