Early one morning last week, outside the A train stop on Utica Avenue in Bedford-Stuyvesant, Darlene Mealy was passing out glossy campaign literature that detailed her fight against a new community parole office.

A New York City Transit employee and rank-and-file union member who is backed by her former boss Reverend Al Sharpton and by the Working Families Party, Ms. Mealy is locked in one of the year’s most competitive City Council races. She is up against more than a dozen candidates, including William Boyland Sr., a former member of the state Assembly who has come out of retirement to run for the seat that his daughter, Tracy Boyland, is vacating because of term limits.

While this year’s Democratic mayoral contest has gobbled up most of the political coverage in newspapers in recent months, there are seven open council seats and a handful of fierce races against incumbents. Most of those contests will be decided Tuesday, when voters go to the polls for the Democratic primary. In the current council, Republicans hold only three of the 51 seats.

Many of those races are expected to play an influential role in the mayoral primary, raising turnout in key neighborhoods for each of the four candidates. And, in addition to ushering in new political blood, the mix of new council members is likely to determine who becomes the next speaker.

Five of the open seats are in Manhattan, one is in the Bronx, and one is in Brooklyn. But some of the most interesting races are the ones against incumbents.

In Riverdale in the Bronx, a business executive, Ari Hoffnung, is challenging Council Member G. Oliver Koppell, a former state attorney general. Mr. Hoffnung, who has racked up a number of union endorsements, has accused Mr. Koppell of being a “part-time” representative. Yesterday, Mr. Koppell said his opponent’s platform was riddled with falsehoods and accused Mr. Hoffnung of running a “nasty negative campaign.” Mr. Hoffnung denied that and said the community needed a full-time representative.

While Council Member Hiram Monserrate of Queens, a former police officer who represents Corona, Elmhurst, and Jackson Heights, does not appear to be in jeopardy of losing his seat, one of his opponents, Marlene Tapper, is accusing him of neglecting English-speaking constituents.

“Hiram’s decided the only people who should be taken care of are the Spanish-speaking community,” she told The New York Sun.

Ms. Tapper, who served as state political director for General Wesley Clark’s presidential campaign, said yesterday that Mr. Monserrate sponsors outreach programs in the Hispanic parts of the district while forgoing other areas.

Mr. Monserrate called the allegations “ridiculous” and “baseless.” He said that his district was close to 70% Hispanic but that he works with constituents of all races and backgrounds in the district.

Council Member Allan Jennings, most widely known for the sexual harassment allegations against him, has several challengers in his Queens district, including a former council member, Thomas White, who is backed by the borough’s Democratic Party.

Other incumbents who have tough races include James Sanders Jr. and Helen Sears of Queens, Larry Seabrook of the Bronx, and Vincent Gentile, Kendall Stewart, and Yvette Clarke of Brooklyn.

Then there are the open seats. Two of those seats are in Harlem, where incumbents Bill Perkins and Philip Reed are being forced out by term limits. Two are on the East Side, where the council speaker, Gifford Miller, is similarly forced to leave office and is running for mayor, and the chairwoman of the council’s education committee, Eva Moskowitz, is leaving the council and running for borough president.

One of Mr. Miller’s top council staff members, Jessica Lappin, is the favorite to replace her boss, while the other seat has several strong con tenders, including a litigator, Daniel Garodnick, and a former prosecutor in the district attorney’s office, Jack Lester.

Uptown, the competition is even fiercer. Six candidates are running for Mr. Reed’s East Harlem seat, and a stunning 10 are running to replace Mr. Perkins, who is also in the crowded field of Democratic candidates for borough president.

Two of the leading candidates in the Perkins district are Inez Dickens, a district leader who has the backing of the elite Harlem political establishment, and Yasmin Cornelius, a community board district manager and community activist.

The candidates have all been passing out fliers at subway stops and making the rounds of community meetings. Yesterday, Joyce Johnson, a former Bronx charter school administrator running for Mr. Reed’s seat, started her morning at P.S. 163 on West 97th Street and spent the day stumping the district.

In the Bronx, where member Madeline Provenzano is leaving her seat, a former assemblyman, Stephen Kaufman; a community board member, James Vacca; and a union leader, Joseph McManus, are in a tight race.

No matter who wins Tuesday, Manhattan will have a less senior delegation, with five new members.

A professor of political science at New York University who is an adviser to Mayor Bloomberg, Mitchell Moss, said: “Everybody is going to look at how this shapes up for the speaker’s race. That’s really a very big wild card.”