Rep. Tammy Baldwin has the opportunity to become the nation's first openly gay Senator, but the race thus far has steered clear of social issues - including her sexual orientation. That is why an email from her opponent's political director questioning her "heartland values" and featuring a video of Baldwin at a 2010 gay pride parade drew so much attention.
"The Thompson campaign has consistently stressed Baldwin's liberal voting record in Washington, and so we're going to see a campaign that paints her as a very liberal, out of touch with the state outside of Madison - and there's a lot of things wrapped up in that, potentially including her sexual orientation," said Charles Franklin, the director of the Marquette Law School Poll and visiting professor of law and public policy at the university. "But it's very hard to suss out how much that plays a role, above and beyond ideology."
Sainz, for his part, disputed that the GOP's "Madison liberal" tag for Baldwin has anything to do with her sexual orientation.
"It's something that is used an awful lot of times," Sainz said. "I used to live in Colorado, if Mark Udall was called a Boulder liberal one more time, I was going to throw up."
From a strategic perspective, attacking Baldwin personally could be risky. Overly personal attacks - like that from the campaign of former North Carolina Sen. Elizabeth Dole (R) charging that Democrat Kay Hagan was a "godless heathen" - have not only backfired, but also arguably decided elections for their targets.
"My impression, just watching a lot of the ads around the country is that the really nasty campaign ads that are over the top really backfire," National Republican Senatorial Committee Chairman John Cornyn (Texas) said, adding that the campaign in Wisconsin, like those across the country, will be focused on the economy.
Cornyn, who said he was "not aware" of the Thompson aide incident, said establishment Republicans likely would not pursue a line of attack based on Baldwin's sexual orientation but that it is still possible one of the many, well-funded outside groups could wage a campaign on the issue in the Badger State.
"Well that's one aspect of our broken campaign finance system is yes, anybody who is able to raise money can come in and essentially hijack the campaign, that's where we are," Cornyn said. "So the candidate can't control that."
Thompson has been strapped for cash after a bruising primary - he held a fundraiser in Washington, D.C., on Wednesday night pulling $1,000 to $5,000 per person, according to an invitation obtained by Roll Call - and has yet to go on the air with ads against Baldwin.
It remains to be seen whether his campaign will run character ads, though if the campaign chose to do so it would not be without provocation. Baldwin's campaign has been running attacks against Thompson, questioning his post-gubernatorial life, his ties to lobbyists and his refusal to release tax returns.
Sources say that Thompson's public repudiation of his aide's behavior, while positive and necessary, still leaves questions over whether his position is the one maintained by his entire staff and his supporters statewide. In an interview with the Milwaukee Journal Sentinel, the Thompson aide responsible for the email did not specifically express regret that he sent it. Attempts to reach Thompson's campaign for comment were unsuccessful.
It's still difficult to say how much sexual orientation ultimately will factor into voters' decisions, mostly because there's not an abundance of data available and because Thompson is averaging a 9-point advantage over Baldwin.
Senate Minority Leader Mitch McConnell, R-Ky., carries a musket on stage as he speaks during the American Conservative Union's Conservative Political Action Conference (CPAC) at National Harbor, Md., on Thursday March 6, 2014.