Call it a bold canvassing move that paid off: An organizer for the Human Rights Campaign asked Sen. John McCain's (R-Ariz.) wife Cindy to sign a postcard Thursday urging the senator to back legislation barring workplace discrimination on the basis of sexual orientation and gender identity.

She signed it.

The senator has never supported the Employment Non-Discrimination Act, which passed a Senate committee in July and could come to the floor for a vote soon. A bipartisan coalition  has dispatched field organizers in seven states across the country to mobilize constituents on behalf of the bill, and HRC has collected "tens of thousands of postcards" as part of the effort, according to HRC spokesman Michael Cole-Schwartz.

Arizona is a key state, since activists are targeting both McCain and his fellow Republican Sen. Jeff Flake; McCain has opposed the bill in the past, while Flake has not voted on the issue since taking office in January.

HRC organizer John Gomez spotted Cindy McCain at a Staples in Phoenix, Cole-Schwartz wrote in an e-mail. "He talked with her about our efforts to pass ENDA, and she shared her support for the bill," Cole-Schwartz said, adding that she signed the postcard and addressed it to her husband.

At the moment, it does not appear that Cindy McCain has changed her husband's mind. In an e-mail, McCain's spokesman Brian Rogers wrote, "Senator McCain enjoys and appreciates having discussions on the important issues of the day with all the members of his family, and he respects their views."

The measure, which bars discrimination against gay, lesbian, bisexual and transgender Americans, stands a better chance of passing the Senate than the House. The Senate failed to pass a similar bill by a single vote in 1996, though that measure did not include gender identity safeguards.