The man recognized Tiffany T. Alston as she stood in line at Chipotle at Annapolis Mall.

“You’re that delegate who didn’t show up,” he said accusingly.

Recalling the incident in her office a few days later, Alston tried to explain what had motivated her to co-sponsor a bill to legalize same-sex marriage only to leave the Maryland House Judiciary Committee hearing room last week just before it came up for a vote.

“I had no idea what to do,” said Alston (D-Prince George’s). “I feel really strongly that people who love each other should be able to get married, no matter what their gender. But I also realize that that’s not my function here. I’m here to represent the 110,000 people back home, many of whom had called and e-mailed and said, ‘We don’t want that bill.’ ”

So the freshman lawmaker took a respite, in the form of a 15-minute ride around the picturesque State House with her chief of staff and longtime best friend, Nefetari Smith, and another state delegate, Jill P. Carter (D-Baltimore), who was also holding out.

The break helped her come to terms with her conflict, and she returned to her office determined to vote no, as her constituents had demanded. The problem was that by the time she returned, the voting session had been postponed and the halls of the House were abuzz.

“I came in later, and there were all these reporters with microphones sticking them in my face,” she said. “They don’t realize how unnerving that is.”

It has been an unnerving two weeks for Alston, as the same-sex marriage bill has built up steam the likes of which it never had before. The measure might come up for a vote in the House on Friday. Should it pass, opponents have pledged to raise enough signatures to send it to a referendum, which Alston supports.

With a little more than two months as a member of the House of Delegates under her belt, Alston has read through reams and reams of research and conducted research of her own. She has learned the byways of the State House and tried to navigate peacefully between the old guard and the new blood.

She admits that she is having some trouble reconciling what she thinks is right with the will of the people. But she wouldn’t have it any other way. That’s when she comes back to the conversation with the man in Chipotle.

After she explained her position, she asked his opinion of the bill. He opposed it. She urged him to contact his legislators.

“Y’all politicians do what you want, anyway,” the man told her.

“You have to make your voice heard,” she told him.

“Honey, you are new,” he said.

Alston said it was that kind of thinking that led her to politics. “We send our soldiers off, sometimes to die, to tell people that ours is the best damn government in the world, so we can’t bastardize that by not letting the people have their say,” she said.

Mr. Smith went to Washington. Ms. Alston went to Annapolis.

Alston is the middle child of three raised by her mother in central Prince George’s County near the D.C. line, and she learned early about the importance of giving back.

In 1988, she was the fifth-grade class vice president at Seat Pleasant Elementary School, with plans to make something of her life, when Abe Pollin arrived at the school to make a speech. Pollin owned the basketball team then called the Washington Bullets and the nearby arena, the Capital Centre, where the team played. And he offered to pay for college for any Seat Pleasant fifth-grader who graduated from high school.

Seven years later, Alston had shown her promise, and Pollin kept his.

She was an honor student, a member of the newspaper staff and a student government leader when she graduated from Central High School in Capitol Heights. Pollin put her through the University of Maryland at College Park, where she received a bachelor’s degree in criminology and criminal justice.

Then, she decided to take a break.

“I had a friend in my physics class at Maryland who said she was going go Ireland to figure her life out after college,” Alston recalled. “I thought that was so freeing and liberating, I decided I was going to backpack through Europe. My mother told me: ‘You are not white, and that’s not happening. You can go into the military, get a job or go to law school as you have always talked about doing.’ ”

She worked as an intern at the Justice Department and looked for a law school. When a friend invited her to attend a Bible study one day at the University of the District of Columbia, she saw an opportunity.

“At one point I went upstairs from the Bible study to admissions,” she said.

Law school, she said, was “the best three years of my life.” As a law student, she worked at a clinic that helped HIV/AIDS patients organize their affairs for their children.

She took a year off after law school to study for the bar and spend time with her infant daughter. She then worked as chief of staff for the Maryland commissioner of correction until she became co-owner of a Lanham law firm where she practices family and business law.

When Pollin died in 2009, she started to contemplate running for office.

“When Mr. Pollin passed away, it made me think about all the things in life that I wanted to do that I hadn’t done,” she said.

On the day of the primary in September, she was racked with anxiety. Her campaign had been staffed by relatives and friends from as far back as elementary school, and they were with her that night at her Mitchellville home as she waited for the results.

“At one point, my sister took me to Buffalo Wild Wings down the street so I could just breathe,” she said. “We waited for what seemed like an eternity for the results to come in. . . . Even when they did, I didn’t believe it. I drove everybody crazy because I wanted the official results.”

On her first visit to her House office, she and Smith, her chief of staff, argued over where to put her desk. “I wanted it positioned so that I could look out the window. She said that looked stupid,” Alston said. “My desk now sits so that I can look out the window.”

Her days run from about 9 a.m. until “whenever,” she said. Some nights she stays over in Annapolis. Sometimes, even though she might not finish until 2 a.m., she heads back to Prince George’s to spend a few hours with her husband, Kendal Gray, an accountant, and their 8-year-old daughter.

As she prepared for the vote on same-sex marriage, she expressed confidence that she had done the right thing. On the day she disappeared, she said, “I needed to think. I needed to pray. I needed to sort it all out.”

She has. “Now,” Alston said, “democracy just has to take its course.”