The political debate over contraception has allowed members of each political party to entertain fantasies about the private excesses of the other.

I’m not talking about sex.

We know that this election will be about taxes, the size of government, and America’s place in the world. We know there will be energy, education, and defense policy speeches. We see all of that coming in slow steady steps. But what quickens the pace of presidential campaigns and sends it into crazy corners is the secret reveal: the moment where one candidate or party slips and gives us a window into their entire world-view. With the contraception debate, both parties are exposed.

For Republicans, the original Obama contraception policy—which required Catholic hospitals to cover their employees who used it—is an example of what they’ve been complaining about all along. The White House will pass policies in the dead of night that infringe on your most sacred beliefs. They were caught this time, but there are hundreds of other secret offenses in the works, plots yet to hatch that will trample on our rights as citizens. You don’t need to think that Barack Obama is evil to worry about these plots. He thinks he’s actually trying to “help.” As Sen. Scott Brown put it, “Basically the government is saying, ‘Just do what you’re told, and leave the moral questions to us.’ “

The Democratic mind has even more kindling to fire the imagination. This week House Republicans held a hearing on contraception but invited no women to testify. Foster Freiss, Rick Santorum’s key financial backer, joked that women used to prevent pregnancy by putting an aspirin between their knees. Santorum has promised that as president he will use the bully pulpit to speak out against sex for purposes other than procreation. “One of the things I will talk about that no president has talked about before is … the dangers of contraception in this country, the whole sexual libertine idea …[Contraception’s] not OK, because it’s a license to do things in the sexual realm that is counter to how things are supposed to be.” In response, Democratic Sen. Patty Murray wrote in a fundraising appeal: “I feel like I woke up this morning on the set of Mad Men. … Republicans have set their time machine for the 1950s.”

Whoever paints the darker fantasy has the political advantage. Ardent supporters already believe the worst about the other side. It’s the independent voters who are at stake. They want government to focus on the big things—the economy, education, defense—and not go too far in either direction. In this election, the choice is between President Obama (the overreach you know) and the GOP nominee (the overreach you don’t know).

If that’s the case, it should be good news for Romney, who argues that he will be a better general election candidate than Santorum. Romney is a man of convictions—he’s devoted to his wife and his religion. He is also a man of malleable views. The wax gets softer the hotter the politics. An independent voter—who wants to see progress and not ideological fights—can easily imagine that a future President Romney would compromise at the first sign of controversy.

That is not true of Rick Santorum. He is far more likely to stick to policies that match his socially conservative views. That is the liberal caricature—but also the fervent belief of Santorum’s own supporters. Santorum has risen to the top in large measure because he has been a brave advocate for hot-button issues like contraception. When he was in the House and Senate, he was the point man on social issues, fighting the good fight when other issues grabbed the public spotlight or other politicians were too afraid to step up. He has won some measure of support because he promises not to bend to the New York Times or lose his focus once in office.

Santorum’s views on social issues are not the sum total of the Santorum campaign. As Dave Weigel points out, Santorum is working hard to show he has appeal beyond the social issues. But he can’t downplay his cultural positions too much because that would be just the kind of cowardice traditional politicians engage in when they get in office.

It is a tradition of politics that you try to scare up the secret text your opponent reads at night to expose him as a closet radical. That’s why Newt Gingrich mentions community organizer Saul Alinsky in nearly every speech. It’s what John Kennedy’s opponents saw in the Catholic Church, and it’s surely the subtext of some of the fascination with Romney’s Mormonism. Whether there’s a secret revealed in the contraception debate will be apparent in about nine months.