State Rep. John J. Toomey, a Democrat from Cambridge, may be retiring a few years earlier than he had planned.

The 67-year-old legislator, who represents the Cambridgeport, Central Square and Inman Square areas, faces perhaps the toughest challenge of his career this November 2. Although Toomey breezed through the Democratic primary unopposed, three Independents are on the ballot to challenge him for the seat he has held since 1943.

One of the Independents, Joseph L. Carson, has already withdrawn from active campaigning, and the second, Bernard N. Bane, isn't given much of a chance. But the third, City Councilor Saundra Graham, is waging a vigorous campaign and has a good shot at upsetting Toomey.

Graham, 35, has served five years on the Cambridge city council, and is well-known throughout the city for her strong support of rent control.

A registered Democrat, Graham says she bypassed the September 14 Democratic primary to run as an Independent because her natural constituency does not usually vote in primaries, and many had not yet registered to vote.

Graham says she will not resign from the city council if elected to the State House, and will seek re-election to one more term on the council.

Holding both seats would not be a conflict of interest, and would make her a more effective legislator for Cambridge, Graham says.

"When I came into the city council, I found that the state legislature has a lot of control over the city. One job will complement the other," she adds.

Toomey, the second most senior member of the legislature, says that he doesn't pay any attention to his opponents, and is running the same type of campaign he always has.

His campaign costs relatively little, consisting mainly of lawn signs, and door-to-door and telephone canvassing, but Toomey says the door-to-door work isn't as effective as it was when he started in politics more than 30 years ago.

Like Graham, Toomey served three terms on the city council. Unlike Graham, though, he is not just a politician. He has been in the real estate insurance business for 40 years. In the State House, he serves on the Ways and Means committee.

Graham is running a more extensive campaign. She has spent about $2000 so far, mostly on subway advertising and printing, and says she has 200 volunteers working for her.

Toomey's district also includes Mather and Dunster Houses, the Leverett towers, and Peabody Terrace.

Both Graham and Toomey say they are running on their records, but Graham is also running against Toomey's. She says he has been "nearly invisible" to the people of the district.

Graham also says that Toomey has voted against handgun control, and against mass transit improvements, both of which she favors.

The battle for the fourth Middlesex seat is a classic old incumbent versus young challenger battle, and as usual, the incumbent must be given a slight edge. But Graham, riding her city council visibility and solid support in key areas of the district, is well within reach of the golden dome