Pop quiz: Which Republican presidential candidate supported the confirmation of Sonia Sotomayor?

Hint: It's the same one who endorsed a pro-abortion-rights presidential candidate in an earlier campaign.

Give up? The answer is Rick Santorum.

Santorum was rightly known as a conservative firebrand during his 12 years in the Senate, but the 1998 confirmation vote for Sonia Sotomayor to the 2nd Circuit Court of Appeals was a notable exception, and so was his endorsement of Arlen Specter's bid for the 1996 Republican presidential nomination.

More on Specter, in a moment, but first, the Sotomayor nomination.

This was not a typical Circuit Court nomination. When Bill Clinton picked Sotomayor in June 1997, many conservatives believed her confirmation would put her in a fast track to the Supreme Court. The Wall Street Journal editorial called her a liberal judicial activist. Rush Limbaugh said Clinton was putting her on a rocket ship to the Supreme Court. A vote to confirm her to the Circuit Court, many Republicans believed, would make it hard to vote against her if she was nominated to the Supreme Court.

Republicans, led by Majority Leader Trent Lott, delayed Sotomayor's confirmation vote for more than a year. When the vote finally happened, 29 Republicans - including most conservative stalwarts like Mitch McConnell, Phil Gramm, Jon Kyl and even John McCain - voted no.

Santorum joined every Democrat in the Senate and 24 other Republicans in voting yes. Sotomayor was confirmed by a vote of 67 to 29. It does not appear that Santorum talked publicly about his decision to vote in favor of Sotomayor's confirmation. As many conservatives predicted, she was eventually nominated to the Supreme Court - but not until a decade later.

And as for the pro-abortion-rights presidential candidate Santorum endorsed, when Specter launched a long-shot bid for president in 1995, Santorum - his fellow Pennsylvanian - was one of his few high-profile endorsements.

For Specter, who later became a Democrat, his pro-abortion-rights position was a centerpiece of his campaign. Specter believed that anti-abortion activists were a "fringe" group hijacking the Republican party.

"There are clearly more Republicans who are pro-choice," Specter told Newsday's Susan Page. "Up until now, I am the only person willing to take on the fringe." After Specter dropped out of the race, he led an ill-fated movement to change the anti-abortion provision in the Republican party platform.

Santorum was effectively returning a favor by endorsing Specter despite his aggressive pro-abortion-rights views. Specter had supported Santorum's 1994 Senate campaign.

Six years later, Santorum supported Specter again - this time in his hard-fought Senate primary battle against Pat Toomey. Conservatives targeted Specter for defeat because of his moderate to liberal views on abortion, gun control and government spending.

Among those supporting Toomey's primary challenge to Specter: a certain Massachusetts governor named Mitt Romney.

Santorum not only supported Specter. He ran an ad for him.

"Arlen is with us on the votes that matter," Santorum said in an ad for Specter. "I'm proud to endorse Arlen Specter."

Santorum's critics have put the 2004 ad on YouTube:

Specter ended up with a narrow 51-49 percent win over Toomey in 2004.