Tim Shaffer/Reuters

Hillary Clinton simply meant to respond to anti-vaxers when she wrote the following tweet.

The reaction was instantaneous. #GrandmothersKnowBest became a trending hashtag, drawing cheers and sneers, leaving pundits to wonder if it was indicative of a larger strategy in the much-rumored Clinton campaign to distract from her age as a potential flaw and, instead, deploy it as a strength.

What Clinton’s tweet actually showed was the power of grandmothers as an American voting bloc—a fact that might not come as a surprise to anyone who’s taken an Intro to Government class. After all, the senior-citizen segment of the population reliably goes to the polls come rain or shine, and is heavily invested in the outcome of elections.

But unlike Hillary, the average first-time grandmother isn’t yet a senior citizen. Clinton, at 67, is far older than most first-time grandmothers in the United States, whose average age hovers around 50. These grandmothers aren’t driven by Social Security, Medicare, or other issues of concern to voters over the age of 65.

Say hello to the Boomer Grannies.

These grandmothers are, as the name suggests, baby boomers, part of a generation that was born between mid-1946 and mid-1964. The oldest boomers turn 70 next year, but the majority of boomers aren’t going to be eligible for retirement benefits until closer to 2030. Within this population of middle-aged boomers, women outnumber men.

Boomer Grannies transformed gender norms—by being the first in their families to get bachelor’s degrees, earning the majority of college degrees in their generation; working outside the home; raising children, often singlehandedly; and revolutionizing the concepts of modern motherhood and feminism.

This generation of grandmas is more hip than the crocheting, bingo-playing, anti-technology stereotype would suggest. They’re too young—and perhaps, too cynical—to rely on classic social-welfare programs that drive the older vote, but they are nevertheless invested in issues affecting their children and grandchildren.

It makes a certain amount of sense that the soccer moms of yore are making a reappearance as a key voting bloc. Boomer Grannies are more world-weary than gracious, more educated than docile; their concern for posterity extends beyond the traditional “maternal” interests of education and healthcare. Today, these grandmas are just as interested in the implications of foreign-conflict intervention and tax reform as they are in paid leave and anti-poverty initiatives.

Clinton’s status as a frontrunner in the potential Democratic Presidential field has excited this very demographic, to her advantage. After all, these aging soccer moms are comfortable with a Clinton in the White House. Boomer Grannies greet the former Secretary of State like a rockstar, and often convey that somehow, Clinton “gets” them.

Part of this cohort’s grandmotherly concern for posterity may have to do with its shared experience of parenthood itself, says Laurel Elder, a professor of political science at Hartwick College who, along with Steven Greene at North Carolina State University, has published the only study of how being a mom affects choices at the ballot box.

“We’ve found very consistent motherhood effects,” she told me. “Even when you’re controlling for other variables, motherhood predicts more liberal attitudes. Being a mom makes you more supportive on government spending on education and daycare and on a whole range of social-welfare issues: spending on the elderly, spending on the poor, overall government services.”

But do these effects continue when the kids those moms raised leave the house? That’s a complicated and under-explored question. Elder said that “even mothers of grown children are more liberal.” Members of this younger generation of grandmothers are still concerned about posterity, but are also committed to advancing their own interests, prioritizing women’s workplace issues like equal pay and paid leave.

In general, parents skew conservative on both social and fiscal issues as they age. But this generation of grandparents has experienced a crushing recession that has affected both them and their children, and might retain its liberal tilt longer. That would impact the presidential race.

Surprisingly little attention has been devoted to the political power of Boomer Grannies, and perhaps it’s because they are often clumped together with senior citizens. But the age structure of this country is changing rapidly—the average age of first-time mothers has crept up to about 27. While women of all ages may provide a huge advantage to Clinton, should she run for the White House, it's the women sharing Clinton's grandma experience that offer significant, tantalizing voting power.

Complicating the story of Boomer Grannies is the aftermath of the recession. Many grown children are returning home and relying on these grandmothers for financial and emotional support as they navigate a changed working world. One in 10 American children is living with a grandparent, with a third of those kids counting their grandparents as their primary caretakers. Poverty is often an issue in households headed by grandmas. Young adults living at home for longer are changing not only family dynamics and household finances, but also the standard model of the nuclear family.

To be sure, having a grown child doesn’t necessarily mean that a middle-aged mother is a grandparent. But the liberal tilt of the soccer mom generation that put Bill Clinton into the White House during the 90s brings up a pertinent question for Republicans: Does the GOP have any prospect of capturing this slice of America?

National Journal’s Next America series found that the traditional Republican strongholds of Nevada, Colorado, and New Mexico are weakening. Romney gave up on New Mexico in 2012, despite the state having a Republican governor. Analysts point to the increasing Hispanic populations in this trio of Southwestern states, contending for power with older, white voters. Hispanic voters are increasingly vocal in politics, and tend to disagree with older voters when it comes to immigration policy, welfare programs, and economics—a phenomenon that has become known as the “brown vs. gray.”

Increasing diversity, however, may not help the Democrats as much as they hope: A report from the Census Bureau notes that “The race and ethnic composition of the baby boom population reflects the composition of the U.S. population during the mid-twentieth century—the years when these cohorts were born.” American baby boomers are overwhelmingly white, with 72 percent of the population identifying as non-Hispanic White. With baby boomers becoming a more female dominated group as the years pass by, that means the exact type of voter that will become crucial come 2016 is a white, educated, working, middle-aged woman.

That doesn’t mean candidates should simply forget about black, Asian, and Hispanic middle-aged women—doing so would be a strategic error. But the more diverse young voters in these states are less likely to turn out for elections, making it possible that older white voters may still secure these states for Republicans come 2016.

Boomer Grannies, on the cusp of becoming senior citizens, are confronting a fragile future with a hazy forecast on Social Security: President Barack Obama’s administration has taken the stance of many Democrats in shifting Social Security’s trust funds to avoid slashes in disability payments, but Republicans have characterized this as “kicking the can down the road,” urging Democrats to consider a more immediate solution for baby boomers now verging on retirement.

The recession has significantly altered the working lives of Boomer Grannies, who have often turned out to be the sole breadwinners for their families as they struggle to pay bills. Obama’s State of the Union speech devoted a significant amount of time to the plight of the American working woman, but the method of doing so by raising taxes irked Republicans, who saw this as an unnecessary step and potentially harmful to the country’s cautious economic improvement.

These rifts in policy are promising for a party that has struggled to capture the votes of older women. Republicans saw a glimmer of hope in the last presidential election, when Obama did shockingly poorly among college-educated white women, a surprising fact given that both college-educated voters and women tend to favor Democrats.

Early polls from a set of Quinnipiac surveys indicate that Clinton enjoys overwhelming support among college-educated white women. But she cannot take much comfort in that lead. “In 2012, Obama lost ground with them, falling back to 46 percent nationally, the weakest performance for any Democratic nominee since Michael Dukakis in 1988,” wrote Ronald Brownstein in National Journal.

Even the subset of Boomer Grannies who identify as Democrats may split. Senator Elizabeth Warren, who most recently denied any interest in running for President, maintains strong support among this very demographic. Warren’s experiences as a baby-boomer mother who has fought financial institutions and Congress in the name of working women means she will have strong support among Boomer Grannies, no matter how many times she says she's not running. And to Warren’s advantage? She’s a grandma, too.

So did Hillary Clinton simply stumble on a demographic that she is uniquely poised to attract? Or does she have a team of strategic consultants who have taken her time on the campaign trail in 2008 to heart and combined with the big data-targeted, get-out-the-vote aggression of Barack Obama? It’s probably a mix of both.

If the Boomer Granny postulate proves anything, it’s this: Whoever runs for president from either party will need to reach out not just to middle America and undecided voters, but also to the middle-aged women formerly known as soccer moms.

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