A coalition of voting rights groups and civic activists is promising to file a lawsuit if the City Council signs off on a map drawn by City Councillor Bill Linehan tomorrow.

Linehan, who chairs the committee tasked with redrawing the boundaries of City Council districts, is hoping to advance his map at tomorrow's Council meeting. The council, which is scheduled to meet at noon, could vote on the map.

“If Linehan’s map passes tomorrow, we will be suing," said Cheryl Clyburn Crawford, co-director of the group MassVOTE, which is a part of the Communities of Color Coalition.

The coalition also includes NAACP-Boston, Chinese Progressive Association, ¿Oíste?, the Lawyers Committee for Civil Rights and Economic Justice and Project HIP-HOP.

The redrawing of the districts is required to occur every ten years, after the U.S. Census releases population figures.

"We’re very disappointed that we weren’t able to negotiate something, that we have to go this route," Crawford said Tuesday afternoon.

Voting rights activists won a similar lawsuit about ten years ago after State House lawmakers redrew legislative district boundaries. Activists claimed the boundaries diluted minority voting strength and protected incumbents. The lawsuit led to House Speaker Thomas Finneran's resignation and subsequent indictment. Finneran eventually pleaded guilty to obstruction of justice and he was disbarred by the state's highest court.

The coalition alleges that the Linehan map violates the Voting Rights Act of 1965 and "packs" District 4 with 95 percent people of color, diluting the potential impact of minority votes elsewhere in the city, like Dorchester's District 3. The groups had proposed splitting District 3 and 4 horizontally, with District 3 in the north and District 4 in the south, instead of the east-west split currently in place.

Linehan did not immediately respond to a request for comment.

District 3 Councillor Frank Baker said he is still deciding which way to vote tomorrow. “I’m still thinking about it. We’ll see what happens on the floor," he said. "There may be amendments."

Under Linehan's plan, Baker picks up the Polish Triangle (Ward 7’s Precincts 8 and 9) and loses two Lower Mills precincts (Ward 17’s Precincts 12 and 14). But he also also gains Ward 7 Precinct 7, which includes Carson Beach, and Ward 7 Precinct 10 and Ward 13 Precinct 5.

“The city is gaining population in the north so we need to shift to the north; my district does," Baker said of the proposed map.