Staff members to Council member Muriel E. Bowser listen to tenants of Mount Vernon Plaza apartments, on Oct. 27, 2014. (Aaron C. Davis/The Washington Post)

More than a dozen residents of a D.C. apartment building and advocates for the poor staged a sit-in Monday at the council offices of Muriel E. Bowser (D-Ward 4).

Members of One D.C., a social justice group, said they had unsuccessfully requested a meeting with Bowser, the chair of the committee with oversight of housing issues, since July regarding rising rental costs at Mount Vernon Plaza apartments.

Under terms of public loans and grants to the property dating to the 1980s, owners of the building had long been required to maintain more than 60 apartments as low-rent units. That obligation recently expired, and tenants in the building near the Walter E. Washington Convention Center began receiving letters warning that rates would increase $500 to $600 a month, or about 50 percent. Rents would rise again next year by a similar amount, the letters said, to reach market rate. The Washington City Paper first reported the issue.

Bowser, the Democratic nominee for mayor, was not at her office as the protesters began arriving, many wearing T-shirts with the logo for One D.C. Her staff summoned two security guards, and the guards allowed only six people into Bowser’s office, one for each seat in her waiting area. The others were forced to remain outside in a hallway.

Robert Hawkins, Bowser’s legislative director, met with the six. They demanded emergency legislation requiring more advance warning for tenants who could see rents skyrocket. They also asked for public assistance to temporarily offset the rising rates at Mount Vernon.

Members of One D.C. wait in a hallway outside Bowser's office, Oct. 27, 2014. (Aaron C. Davis/The Washington Post)

Tenants in roughly four dozen buildings across the District could experience similar situations in coming years as affordable-housing covenants expire in downtown areas where rents are now among the highest in the national capital region.

Advocates emerged from the meeting with Bowser’s aides saying Hawkins had told the group that Bowser would return and draft emergency legislation to help.

Hawkins later said that was a mischaracterization and he met with the advocates for a second time in the afternoon to flesh out possible legislative remedies. He said Bowser planned to meet with the group on Tuesday afternoon.

The council’s final meeting before the Nov. 4 election is Tuesday. The Mount Vernon issue echoed one earlier in the fall when Council member David A. Catania (I-At large) and Mayor Vincent C. Gray’s administration introduced legislation to help residents of Museum Square, many of whom are on public assistance. They were asked to come up with hundreds of millions to purchase the property or to leave.

A phone call to Mount Vernon Plaza was not immediately returned.

This post has been updated.