Who among us hasn’t spent a date night fighting over the merits of a renewed cap and trade act?

You haven’t? Yeah, neither have we. But that doesn’t mean politics haven’t been seeping into our relationships in ways big and small, especially in an election-year climate as divisive and colorful as this one.

The “Single in America Study” of more than 5,000 U.S. singles age 21 to 65 looked at, among other things, the role of political leanings in dating and found that our voting habits are frequently reflected in our love lives: in the type of partners we seek out and how we conduct ourselves within those partnerships.

While only 17 percent of men and 20 percent of women said a partner with the same party affiliations is a “must have,” the findings suggest singles may do some self-selecting that falls along party lines, even if unintentionally.

Self-described liberal Democrats, for example, place the highest priority on finding a partner who “treats them with respect,” “has a sense of humor” and “is comfortable with sexuality,” according to the study, which was sponsored by Match.com and conducted by biological anthropologist Helen Fisher and relationship therapist Laura Berman. Republicans’ top priorities are “shares the same values,” “has the same view on money” and “is the same religion.”

Democratic men consider it a turn-on “if a date is opinionated.” Self-described conservative Republican men consider it a turn-on “if a date dresses conservatively” and a turn-off “if a date has many guy friends,” while moderate Republican men consider it a turn-on “if a date is career-driven.”

“If you look at brain chemistry research, there are a lot of both nature and nurture underpinnings to one’s political viewpoints,” says Berman. “If you’re raised in a certain environment, taught certain things, lived in a certain community, maybe you tend to be more of a rebel or risk taker, maybe you tend to be more conservative.”

In other words, our political views, at some point, blend together to become our world views.

Which is partly why, say relationship experts, it’s next to impossible to keep politics out of the picture, “even if you’re not sitting down and saying, ‘What are your views on abortion, contraception and gun rights?’ ” says Judith Kuriansky, a psychologist on the faculty of Columbia University Teachers College and author of “The Complete Idiot’s Guide to Dating” (Alpha). “Political discussions have bled into people’s dating lives in such a big way: where they stand on the economy, taxes, Social Security, social services.”

Kuriansky attributes the seepage to a dating population that’s older and more politically aware than ever, but also to the general economic malaise gripping much of the nation.

“Across all ages and relationships more people than ever are sitting in counseling discussing what’s happening in the world and where the world is going,” she says. “The life stresses have created a real psychological depression about the economy, about the future and about the present.”

Indeed, singles in the study listed the economy as the No. 1 source of stress in their lives.

“People are so aware of how much money they have now, how much they’re going to have later and what kind of life they are able to have,” says Kuriansky. “Money is so much in the forefront of people’s minds.”