(FORTUNE Magazine) – The convention season is heating up, and so is another pastime: online dating at sites geared toward the politically like-minded.

Most say that Howard Dean's Internet-fueled campaign laid the groundwork for partisan dating. John Hlinko, a political consultant in D.C., realized he was spending so many hours online searching for both love and political information that he decided to combine his interests in the spring of 2003 by launching ActForLove.org, a dating website for liberal activists. After taking a short hiatus to build DraftWesleyClark.com and then to run Wesley Clark's Internet strategy, Hlinko returned to his Internet project this spring. By that time he had some new competition: RepublicanSingles.com and DemocraticSingles.com, both started by Tony Sandoval, CEO of Terra9 Singles, which operates five dating sites.

"A few years ago the Internet couldn't have [supported] a lot of these niche sites, because there just wasn't critical mass online," says Nate Elliott, an associate analyst for Jupiter Research. But now, with two out of five singles browsing dating websites, more sites are starting to splinter off into niches. Not that the numbers are exactly staggering: Sandoval says that 2,400 users have signed up on his Republican site, and only 700 on his Democratic one. Another site, SingleRepublican.com, saw traffic triple to 3,000 after running ads on FoxNews.com in June.

But the sites do attract a rather diehard bunch, which bodes well for finding future running mates. Says Hlinko: "If you are so impassioned when it comes to politics, it is just a few short steps to passion about something completely different." --Julie Schlosser