Republican candidates are deep in debates and President Obama is deep in campaign mode for the 2012 election, but one issue remains under the surface. The future of Barack Obama—and America—rests with the voting preferences of a frequently overlooked group: unmarried women, who make up about 25 percent of the country’s voting population.

The liberal research, polling and strategy firm Greenberg Quinlan Rosner (GQR) found after the 2008 election that, "If not for the overwhelming support of unmarried women, John McCain would have won the women's vote and with it, the White House." Unmarried women voted for Barack Obama over Sen. John McCain, 70 percent to 29 percent—and cast 23 percent of all votes in that election.

In 2010, GQR found that unmarried women continued to vote strongly for Democratic candidates. But a sufficient number of some unmarried women switched votes, and that helped carry many Republicans to victory. The Los Angeles Times cites a GQR analysis that in 2010, all Republicans running won the vote of half of white unmarried women. That was up from just 39 percent of support from that group in the two previous election cycles.

GQR’s pollster Anna Greenberg explained that, "Unmarried women are the most economically vulnerable group, particularly if they have children. While there has been a lot of discussion in this recession about men and manufacturing jobs, it still is the case that unmarried women are the poorest. If they feel their concerns aren't being addressed by Obama and the Democrats around the economy, it sort of makes some sense there was a decline."

Besides jobs and the economy, unmarried women are also concerned about how much health care coverage they’ll receive—or lose—under ObamaCare and about changes made to programs like Medicare and Medicaid.

Another source of their anxiety is the future of Social Security, which more than 25 percent of unmarried women rely on as their only source of income.

Improved education as a path to economic improvement—for their children, grandchildren and themselves—is another high priority for unmarried women. Eighty-four percent of single mothers lack a college degree.

GQR’s post-2010 election analysis of the main swing voters among unmarried women—white women—found that the top two issues that rankled them most about elected officials in Washington were “too much political party bickering” and “too much spending, taxes and deficits.”

Surely, many other issues will be on the minds of unmarried women in the 2012 election, including the proper role of government in matters running the spectrum from economic security to national security.

Unmarried women also will share with other voters a very personal, emotional reaction to whoever is running for office.

Metaphorically speaking, in 2012 the nation will decide which person, which set of policy prescriptions, and which values it prefers to be “married to” for the next few years, in contests ranging from the White House to various state and local races.

The personal appeal of each candidate—how he or she makes unmarried women feel—will be a critical factor in the outcome. Unmarried women voters will be looking for what others seek in candidates: credibility based on a proven track record, and likeability based on personality and communication skills that show a combination of authority and warmth.

By their sheer numbers, unmarried women have the power to influence America’s leadership course if they are motivated enough to get out and vote. Rallying their participation and support will be a challenge for candidates and advocacy groups.

Whether the prospect of an election that could turn on the votes of unmarried women makes you nervous or excited, it would be a mistake to ignore how important winning them over will be in 2012.

Communications consultant Jon Kraushar is at www.jonkraushar.net.