The margins for confirming Supreme Court Justices are getting tighter:

Though it confirmed her Thursday as the newest justice by a 63-37 vote, Kagan has the dubious distinction of receiving one of the lowest total of “yes” votes for a nominee during the past three presidencies — and the lowest number of confirmation votes ever for a justice picked by a Democrat.

Kagan’s meager tally is five fewer than Sonia Sotomayor last year, 15 fewer than John Roberts got in 2005 and pales in comparison to the 96-3 coronation of Ruth Bader Ginsburg in 1993. That trend has many legal observers lamenting a Supreme Court confirmation process on a steady trajectory toward complete polarization and a seemingly inevitable filibuster.

“We are well on our way to a huge train wreck,” said Tom Goldstein, a veteran Supreme Court litigator. “I do think this is a corner we won’t be able to turn back [from], or at least there’s no sign the Senate will turn back from, for a long time.” If 60 “yes” votes “is the best anyone is going to have, a Supreme Court confirmation fight could easily turn into thermonuclear war."

Bear in mind that, before Obama picked her, Kagan was touted as the consensus pick most likely to gain Republican support. (Ginsburg had been head of the ACLU's Women's Rights Project -- imagine a nominee like that getting through the Senate today, let alone with 96 votes!)

The Republican pretense that judicial nominees, and judicial nominees alone, should be entitled to a majority vote is a hangover from a tactical position the party took during the Bush era. Republicans "didn't filibuster" Kagan because they didn't have 40 votes to stop her. After the 2010 elections, their numbers will almost certainly increase to the point where even a moderate like Kagan stands little chance of clearing the 60 vote threshold.

And this has all taken place in a landscape where Obama has merely been replacing liberal justices with other, possibly less liberal, justices. Can you imagine what will happen if one of the five conservatives retires on Obama's watch? It's entirely possible that Senate Republicans will simply refuse to confirm any more justices, period.