Rep. Donna Edwards talked with supporters before a March candidates forum with Rep. Chris Van Hollen. Both are running in the Democratic primary for Maryland’s open Senate seat. (Mark Gail/For The Washington Post)

The Democratic primary for Maryland’s open Senate seat has gotten hotter than a steaming tray of Chesapeake blue crabs. And what’s at stake is about much more than the people of Maryland.

The race pits an outspoken­ ­­57-­year-old African American woman, Rep. Donna F. Edwards, against a progressive 57-year-old white man, Rep. Chris Van Hollen. It raises issues of parity and equality, and the very nature of American legislative representation. It’s about race and gender in American politics. It’s about a looming question in this election season as Hillary Clinton makes her historic run for the presidency: Do you vote for someone because of gender?

Edwards, who lives in Prince George’s County and represents the 4th Congressional District, is running hard for the seat opening up because of the retirement of the Senate’s longest-serving woman, Barbara A. Mikulski (D).

And if Edwards wins the Democratic nomination April 26 — and then the Senate seat in November (almost a given in deep-blue Maryland) — she’d make history as only the second African American woman to serve in the chamber.

Why is this so important?

A new Washington Post poll reveals that voters are split among racial lines when asked to choose between Reps. Donna Edwards and Chris Van Hollen ahead of the April 26 Maryland Democratic primary. (Ashleigh Joplin/The Washington Post)

“When she sits there, we all sit there,” declared Betsy Simon, 76, right after she met Edwards at the Neighborhoods United annual banquet in West Baltimore on Sunday.

“She has lived her life; it’s like our lives,” Simon said. “And she knows what we need.”

Indeed, the underrepresentation of women in government, especially women of color, is a national disgrace.

Only 31 women have been elected to serve in the Senate. Fourteen other women have been appointed to Senate seats — one for just a single day — to replace their dead husbands.

If anyone were to create a portrait of 100 people representing America, could you imagine having zero black women?

How could a group of mostly white men accurately reflect our nation? Except for Carol Moseley Braun, who served a single term in the 1990s, no African American woman has served in the Senate for 227 years.

Until Edwards became a candidate on fire, Van Hollen seemed like a shoo-in.

He’s a solid, well-liked, progressive Democrat from Montgomery County and has had a good track record in state politics. He even has the backing of two of Maryland’s most powerful black elected officials: Montgomery County Executive Isiah Leggett and Prince George’s County Executive Rushern L. Baker III.

Van Hollen’s dedication to working families, public transportation and veterans should show that a guy doesn’t have to be a mom, a bus rider or a retired infantryman to represent those people and the issues important to them, right?

Maybe.

But Edwards — thanks in large part to financial and public support from female-fueled backers such as Emily’s List — is tied with or even slightly ahead of Van Hollen in the polls.

And there’s something to her growing popularity that goes beyond a legislative accomplishments checklist.

On paper and policy, the two candidates are fairly similar. And both would probably serve Maryland’s 6 million residents well.

But what’s fueling Edwards is something bigger than the state’s voters.

The country’s 20 million black women are a mighty force in American life, long serving as part of the backbone of their families and communities. They also matter at the polling booth. In 2012, black women voted at a higher rate than any other group, according to a report on women of color by the Center for American Progress.

Edwards would be a voice for them. And, as a woman who raised a child alone while she went to law school, she would be a voice for the nation’s 10 million single mothers, as well.

Single moms get mentioned a lot in political debates about equal pay, welfare, child care and health care. But how many lawmakers making decisions that affect one of America’s fastest-growing populations have actually been there?

Any single dads in the Senate? Any single moms?

The Senate’s official historians think that the only single mom to serve in the Senate was the first woman elected, Sen. Hattie Caraway of Arkansas. She had three sons in their 20s when she took over the Senate seat of her late husband, Thaddeus Caraway, in 1931.

The only single dad anyone remembers is the current vice president, Joe Biden, the Democrat from Delaware who served for five years as a single parent after the death of his wife in 1972, according to Daniel S. Holt, assistant historian for the U.S. Senate Historical Office.

Although Edwards’s son is 27, her biography as a black single mom is part of the reason why her candidacy is resonating — and why she could upset Van Hollen.

“He just doesn’t know me,” said Katrina Williams-Shelton, 54, a Baltimore teacher.

She couldn’t think of a legislative action or position that Van Hollen has taken that runs counter to her interests. Even so, she said, “He can’t meet my needs if he hasn’t been there and doesn’t know what my needs are.”

There’s a bigger message here. Women nationwide are tired of being underpaid, undervalued, underestimated and underrepresented. And candidates such as Clinton and Edwards exert a powerful appeal on that basis alone.

“For African American girls, to see someone who looks like them in that [Senate] seat means everything,” explained Glenice Shabazz, 44, who owns and operates seven child-care centers throughout Baltimore.

“And for African American women, seeing someone there who knows your struggles, who has lived your struggles, that’s powerful,” Shabazz said after posing for a selfie with Edwards on Sunday.

Edwards went to food banks while raising a child and earning a law degree. Maybe until you’ve been there, until you know what that’s like, you can’t truly know what the needs are.

“I’m not saying we should vote for her just because she’s a woman,” said Kim Truehart, 59, a Navy veteran and community activist in Baltimore who is running for City Council president. “But I’m saying we should vote for her because she brings real diversity.”

And all things being equal, why shouldn’t women vote to make representation equal — at long last — too?

Twitter: @petulad