Three days after headlining the Obama campaign's roll-out of GOP supporters, former Sen. Lincoln Chafee (R-R.I.) announced today that he will join the board of directors for NARAL Pro-Choice America this fall.

Chafee, now an independent, said abortion rights provide a stark difference between Barack ObamaBarack ObamaSpicer: Trump is 'very confident that he will be vindicated' on surveillance claims Bush DHS secretary: 'Vladimir Putin is winning' Trump ally calls for US to roll back climate commitment MORE and John McCainJohn McCainOvernight Defense: General warns State Department cuts would hurt military | Bergdahl lawyers appeal Trump motion | Senators demand action after nude photo scandal Senate lawmakers eye hearing next week for Air Force secretary: report House Intel chairman under fire from all sides MORE, blasting the Arizona Republican for not supporting them at a federal level. Chafee endorsed Obama in February.

"I have always said that being pro-choice is a mainstream conservative value," Chafee said. "It is unfortunate that Sen. McCain does not share the view of many mainstream Republicans that privacy and freedom from government interference in personal decisions is a core value."

"This is one of the clearest differences between Sen. Obama and Sen. John McCain--and it is a difference that matters to voters, including pro-choice Independent and Republican women," Chafee said.

McCain yesterday floated the possibility of tapping a pro-abortion-rights running mate in an interview with The Weekly Standard. McCain has said he would like to see Roe v. Wade overturned, giving states authority over abortion rights, and for the U.S. to work toward ending abortion as a practice.