Republican activists on opposing sides of the gay marriage debate have been treating the upcoming Republican convention battle much like a hotly contested political campaign.

At question is whether the party's platform, its official statement of party values, should oppose gay marriage. The fight to win over the roughly 1,700 Republican delegates to the convention has been waged with the trappings of a professional campaign: Postcards and fliers have been hitting mailboxes, and volunteers have been calling delegates for close to two weeks now.

It's nothing close to the magnitude of the ballot fight that would have resulted if a proposed constitutional ban on gay marriage had made it to this November's ballot. But the same groups that fought over the proposed ban earlier this year have been treating the convention battle in a similar fashion.

Jim Bopp, a Terre Haute attorney who pushed to have the marriage definition added to the platform, said he is confident the marriage clause will make the cut this weekend.

"Nothing is ever a sure thing," he said. But "we feel good in terms of retaining it in the platform."

The first hurdle was last month, at a meeting where the party's platform committee approved the marriage definition being included in the platform. The second hurdle will be a committee meeting Friday, where changes to the platform will be considered. The final bar will be consideration by all delegates at the convention during Saturday's daylong meeting.

Megan Robertson, a Republican delegate from Marion County, is leading the fight against the marriage language. She said Thursday that she had signed up 21 regional volunteers to try and win support from delegates.

"You never know what's going to happen in these kinds of situations," she said. "I'm confident there are number of delegates who don't want to see this divisive language added to our platform."

Robertson, a veteran Republican operative who led the opposition to the proposed marriage ban earlier this year, said she has been trying to ply delegates with testimonials from other delegates who have signed on with them.

Her most recent mailer to delegates quoted Cheryl Musgrave, a Vanderburgh County delegate, saying: "Our party platform should have broad-based support and concentrate on issues involving lower taxes and smaller government. I don't believe the marriage debate is an appropriate thing for a party platform to be discussing."

But supporters of the marriage language have been pressing as well. The leaders of the Indiana Family Institute, which fought unsuccessfully for the proposed constitutional ban this session, sent a mailed flier to delegates.

Bopp, meanwhile, forwarded an email from Rush County Republican Chairman Michael Dora, the author of the marriage language, calling the proposal a compromise designed to please most Republicans. In the email, Dora recounted the events of the platform committee's final meeting, when it voted to accept the marriage language.

"What happened on that day is called 'give and take' or just an old fashioned compromise," Dora wrote.

The Republican Party convention opens Friday in Fort Wayne and will continue all day Saturday. In addition to the marriage battle, Delegates are bracing for a bruising fight over the treasurer's nomination between three candidates: financial adviser Don Bates, treasurer's office staffer Kelly Mitchell and Marion Mayor Wayne Seybold.