DENVER (AP) -- Sara Stevenson spends her working hours surrounded by Republicans, namely the married men who work alongside her in a Denver oil and gas firm company. But after hours and on weekends, she usually spends her time with other single women, and there's not a Republican in sight among the bunch.
"There was just no way I could have supported any Republican this year," said Stevenson, 31. "They skew so much to the religious right. ... They focused so much on taxes. It's not something that women in my demographic really care about. I've never heard my friends lament their taxes."
As Republicans dust off their Election Day drubbing last month, their party must confront the reality that the ranks of unmarried women are growing rapidly, and these voters overwhelmingly have backed Democrats for decades.
Women increasingly are graduating from college and joining the workforce, and postponing marriage. From 2000 to 2010, the number of unmarried women increased 18 percent, according to census data.
Republicans have spent the past month tallying up all their demographic weak spots, including with Hispanics and Asian-Americans. But some warn that single women, already one-quarter of the electorate, represent the most serious threat to the party's viability.
"It's a faster-growing demographic than most others," said Kellyanne Conway, a Republican pollster. "That's a cultural zeitgeist that demands a political response."
In 1960, the average American woman married at age 20. Now it's 27. That reflects, and is partly the cause of, a boom in solo living, with nearly one-third of all U.S. households comprised of single people living alone, according to Eric Klinenberg, a New York University sociologist and author of a book on the subject. In 1950, it was 9 percent.
Around the world, as women gain more education and earn more money, they increasingly are delaying marriage, said Stephanie Coontz, who teaches history and family studies at The Evergreen State College in Olympia, Wash., and is director of research for the Council on Contemporary Families. "Nowadays, women don't feel so driven to get married because they can support themselves," she said. "A lot of this is driven by women and a combination of lowering payoffs to just marrying any man and rising expectations" of what marriage will bring, she added.
For decades, Conway said, Democrats targeted unmarried women while the GOP dismissed them.
In the Nov. 6 election, President Barack Obama's campaign targeted this group in a series of direct mail and email pieces featuring the singer Beyonce and activist Lily Ledbetter, whose name was on the first bill Obama signed, making it easier for women to sue over unequal pay. The campaign also released an online video by actor and writer Lena Dunham that compared a woman's first time voting to losing her virginity.
Now, Conway said, "the Republicans have to decide if they want a one-party response or a two-party response."
In a presidential election dominated by debates over women's health and abortion, unmarried women backed Obama over Republican Mitt Romney by a 67-31 margin. Since 1992, when exit polls began identifying single voters, unmarried women have favored Democrats by similar margins.
Celinda Lake, a Democratic pollster who wrote a book with Conway on the women's vote, said unmarried women are a tough group for the GOP to crack.
"Any way you cut it, this demographic is much more on their own and much more precarious and much more interested in a safety net," Lake said. "If you're married, you're much more likely to be a churchgoer and have your church as a community. If you're married, you're much more likely to have owned your home for a while and have that community to rely on. If you're married, you're more likely to have your spouse to depend on."
Single men are also significantly more likely to back Democrats than Republicans, but that is largely a function of their age, because they are largely younger. Unmarried women, however, are more evenly spread across all age groups and consistently lean Democratic, said Page S. Gardner, president of the Voter Participation Center, which tries to increase voting by single women. They also are much more likely to support abortion rights.
In Colorado, Democrats have assiduously focused on abortion and other health issues to win support from both married and single women. In 2010, Sen. Michael Bennet defied the Republican wave by hammering his tea party challenger on his opposition to abortion rights. This year, Obama campaigned in the state with activist Sandra Fluke, an unmarried law student branded a "slut" by commentator Rush Limbaugh for testifying before Congress in support of requiring that employer-provided health insurance covers contraception.
The Obama campaign attacked Romney on the airwaves over his refusal to support the Lily Ledbetter Fair Pay Act, his opposition to federal dollars for Planned Parenthood and his opposition to abortion rights.
Katy Atkinson, a GOP consultant in Denver, said that two elections in a row should be a warning sign for the GOP.
"That whole fighting social issues with economic issues just doesn't work," she said. Atkinson noted that both Romney, as well as Bennet's opponent, Ken Buck, contended that women really cared about pocketbook issues rather than reproductive issues. "While women care about pocketbook issues, they don't want to elect an extremist."
Conway said the GOP can win over unmarried women on economic matters. "What do women, married or unmarried, do every week?" Conway asked. "Do they fill up the gas tank or get an abortion?"
Lauren Koebcke, 32, is a glimmer of hope for Republicans. She is single, favors gay marriage and abortion rights but sides with the GOP on economic issues. The bad news for the GOP is that she's the only one of her single friends who votes Republican.
"Most people I know are Democrats and most Democrats I know are single," said Koebcke, a project manager in Austin, almost 300 miles west of Denver. "Most Republicans want home and hearth. They want babies and that family life."
Stevenson isn't sure whether she wants a family. "Most of us didn't make any money until we were 26 year old and we want to enjoy ourselves," she said. She logs 11 hour days analyzing legal issues for her energy company. "I can't imagine coming home and having to cook dinner and deal with someone else's problems," she said. "I'm not there yet."
She also knows that Republicans won't be getting her vote anytime soon.
Republican Senate candidates in Missouri and Indiana infuriated her when they tried to explain why they think rape victims shouldn't be allowed to have abortions. Stevenson stayed up late on election night just to confirm that they both lost.
The women's issues that Obama emphasized, such as equal pay for women and contraception coverage, are pocketbook issues to Stevenson. The fact that GOP candidates denigrated them as social issues just shows how out of touch the GOP is, she said.
"There are just so many off-putting comments from the Republican party," Stevenson said. "It's crazy to me that they're still acting as if women are a niche market."
Associated Press Polling Director Jennifer Agiesta in Washington contributed to this report.
Follow Nicholas Riccardi on Twitter at www.Twitter.com/nickriccardi