ABC News Jan Simmonds reports: On ABC News’ "This Week with George Stephanopoulos," former Pennsylvania Governor and Secretary of Homeland Security Tom Ridge reaffirmed his pro-choice position on abortion, and said he did not think Sen. John McCain, R-Ariz., would make it a litmus test on whom he would choose to be his running mate. "I would think John would never make it a litmus test, but when it comes down to a nominee selecting a vice presidential running mate, it’s their decision exclusively," said Ridge. "And I would respect that decision one way or another." When asked whether he thought having a pro-choice candidate at the top of a national ticket would turn off the Republican Party base, Ridge said, "I think, at the end of the day, I think the party would be comfortable with someone Sen. McCain was comfortable with. And that is ultimately his decision." Ridge chose to hold his cards close to the vest, though, when questioned directly about whether he would accept the offer if John McCain makes it. "I would have that conversation with my friend John and report back to you," said Ridge with a chuckle. Ridge also took the opportunity to vouch for the Barack Obama/Britney Spears ad the McCain campaign released earlier this week. "The commercial elevates the whole question of energy policy in a way that some people like, some people don’t like," added Ridge, saying the issue of the ad is an important one. "John McCain has suggested that we have an all-above approach. Let’s talk nuclear, let’s talk drilling, let’s talk biofuels. … Let’s get it all on the table, and Obama — Sen. Obama, excuse me — said no nuclear, no drilling," said Ridge. On the subject of the developments in the anthrax case, Ridge said that while he was secretary of Homeland Security, neither President Bush, nor anyone else at the White House, had pressured investigators to focus solely on al Qaeda. "President Bush and Vice President Cheney, on many of our meetings, were saying, ‘Follow the evidence whereever it takes you,’" said Ridge, "’And cast a universal net worldwide, whether it is domestic, whether it’s international, whether it’s al Qaeda. We need an answer.’" The former secretary added that he did not know if government scientist Bruce Ivins was involved in the 2001 anthrax mailings, adding it’s difficult not knowing the evidentiary trail or how deep they have dug.