Mayor Thomas Menino on Monday vetoed a second redistricting map sent to his desk on a 7-6 vote, again citing an over-concentration of people of color in District 4.

City Councillor Tito Jackson had mounted a surprise push for the map, which redraws the boundaries of district council seats, at the City Council’s Wednesday meeting. The push came after Menino vetoed an earlier map, which was backed by City Councillor Bill Linehan, the chair of the council’s redistricting committee.

“My concern about the last plan was that it concentrated ‘our many citizens of color into too few districts, and in doing so may limit their equal opportunity to elect candidates of their choice,’” Menino wrote, quoting from his previous veto letter from Sept. 6. “This overconcentration was especially true in District 4, and the second map you passed shares the very same problem there and almost the very same figures.”

Menino noted that in both maps, 70 percent of District 4’s voting age population is black and 95 percent is non-white. “In a city where diversity is found broadly, I had asked that you endeavor to avoid over-concentration of minority voters, and I make that same request again.”

A redistricting committee meeting is scheduled for Friday at 11 am in City Hall, and the Coalition of Color, which has pressed for vetoes of the two maps, is invited to state their case, according to Linehan's office.

In a statement released through an aide, Linehan said he was not surprised by Menino's veto. “Based on this veto, the mayor indicates we all have some work to do," Linehan said.

A collection of civic and voting rights groups had pushed Menino to veto both maps, and in its latest call for a veto, had also demanded the removal of Linehan as redistricting committee chair.

The council, which must redraw the maps to account for population shifts revealed by U.S. Census figures, is facing a November deadline. A map must be approved a year before the 2013 election.

UPDATED: This post was updated at 3:56 p.m. with a statement from Linehan's office.