SPRINGFIELD, Ill. (AP) – Deborah Mell stops by the Illinois governor’s mansion after a long day of lobbying at the state Capitol. Having changed from her power suit to a baseball cap, T-shirt and jeans, she is dog-tired – but takes time to dig for a folder full of information advocating for same-sex marriage.

“Will you give this to the governor?” she asks a mansion staff member.

She smiles as she drives away, confident that Gov. Rod Blagojevich, who opposes marriage rights for same-sex couples, will receive the folder. That’s because Mell is the governor’s sister-in-law – a lesbian who has taken it upon herself to fight him on this issue in recent months.

“When Rod got elected, I thought, ‘Wow! Things are really going to be different.’ I thought gay marriage would be one of his issues,” says Mell, whose sister, Patti, is married to the governor. “I guess I was naive.”

It is not unusual for families to be as divided as the country is on the issue of same-sex marriage. But the debate has placed particular attention – sometimes uncomfortably so – on political families with members who are lesbian or gay.

For instance, many Americans are now aware that Vice President Dick Cheney and former House Democratic leader Dick Gephardt of Missouri each have lesbian daughters. And last month in San Francisco, David Knight, the son of California state Sen. William “Pete” Knight, married his longtime boyfriend. The elder Knight, who was not present at the ceremony, is among California’s most prominent opponents of same-sex marriage.

Now Mell has come forward to take on the unfamiliar role of activist.

The 35-year-old daughter of longtime Chicago alderman Dick Mell, she has witnessed many a high-profile political battle – but had never really been part of one, until now. Her involvement began on Valentine’s Day, when Mell, who grew up attending Roman Catholic schools, decided to join a same-sex marriage rights vigil outside the home of Chicago Cardinal Francis George.

Last month, Mell was the only person arrested in a minor scuffle at a pro-marriage rally in downtown Chicago.

Through it all, she has gained recognition as “the governor’s sister-in-law” – most recently using her higher profile to lobby for a bill that would add sexual orientation to the Illinois anti-discrimination code. The bill, which has slowly gained some support over the years, has been around for decades.

But it was the marriage issue that spurred Mell, who is single, to action – in part because she couldn’t let her brother-in-law go unanswered on this issue.

The governor – a Democrat supported by many members of the gay and lesbian community during his campaign in 2002 – said he was a little taken aback by the public role his sister-in-law has taken on this issue, but recognizes that she is free to do so.

“I admire her for fighting for something she believes in,” he says. “It’s a good thing.”

He even said that if Mell decided to wed in Canada, where it is legal for same-sex couples to marry, he would attend “and bring a gift.”

But when it comes to his home state, Blagojevich has no plans to change his position – that marriage, as defined by Illinois law, is “between a man and a woman.”

“I support that law, and I support that definition,” he says, noting that he has no problem with the concept of “domestic partnerships,” but also does not believe Illinois should allow civil unions, as Vermont does.

And even if he did, the concept could be a tough sell in the state Legislature, especially among those who’ve regularly opposed measures related to gay rights – including the anti-discrimination bill.

The governor’s wife, Patti Blagojevich, acknowledges that it’s not always easy to be in the middle – between a husband and sister who “agree to disagree.”

“I love and respect my sister, and I’m proud of what she’s doing,” she said. “And I love and respect my husband.”

Gov. Blagojevich is not, however, the first member of Mell’s family to take an oppositional stance on gay issues.

Her father, Dick Mell, voted in 1986 against a proposed Chicago ordinance to protect lesbians and gay men from discrimination. Deborah, who was 18 at the time, hadn’t come out to her parents yet, though they already suspected she was a lesbian.

After the aldermen soundly defeated the proposal, Dick Mell remembers turning to a colleague and saying, “That was the worst vote I ever made.”

He’s been an advocate of gay rights – and especially his daughter – ever since.

After she was arrested last month, he greeted her – arms outstretched – as she was released from police lockup. She thought he might be angry with her. But instead, he hugged her.

“I’m proud of you,” he said, as they both cried. “You’re a good daughter.”

In the days that followed, daughter and father appeared on television together to, as they both say, “put a face” on the issue.

“I like the idea of some kid in a small town in Illinois hearing about the governor’s sister-in-law,” she says.

Her father said he has received one angry letter, unsigned. But others were encouraging of the self-defined “old school” politician.

One constituent – a physician whose sister is a lesbian – wrote: “I can’t believe I am writing this, but I actually, for once, am proud that you are my alderman.”

Meanwhile, a same-sex couple from a nearby suburb asked: “Can’t you speak to your son-in-law?”

He says he plans to.