BUT SOME observers think Menino isn’t just letting his progressive supporters go their own way while he focuses on his own race. His gamesmanship has more to do with keeping a lid on opposition that could get ugly if he lurches too close to any particular candidate. " He thinks that Lynch is going to win, but he lives in abject fear of the two biggest constituencies in the city — the Irish and the gay, " says one long-time Menino-watcher. " Being out in front is not in his best interest right now. "

For Menino, progressives matter — in part, because he is not a member of the Irish power establishment. Menino’s choice could also help determine whether he gets the support of the Massachusetts Women’s Political Caucus, which backs Jacques but has not yet reached consensus on a mayoral endorsement. " We’re hoping that the mayor will support our candidate in the Democratic primary, " says Ronnie Thaler, the group’s executive director.

Both Lynch and Jacques say they have no problem with the mayor’s role in the race. " Senator Jacques has great respect for Mayor Menino, " says Jacques spokesman Angus McQuilken. " They’ve worked closely together on a number of important issues, including the passage of the toughest gun-control laws in the country. She looks forward to working with him as a member of Congress. " Scott Ferson, a Lynch spokesman, says, " The mayor’s got his own race. Obviously the senator feels very comfortable getting out his own vote in the city of Boston. " Asked whether Lynch feels slighted by the lack of an endorsement at a time when most other city and state officials in Boston have come out in his favor, Ferson says he " doesn’t think it’s an oversight. "

That’s the message of the Lynch people now, while they’re still trying to get their candidate elected. But if Lynch wins — which seems likely though far from certain — that message may change. Lynch is the same candidate whose team was warning potential donors that he would remember those who failed to back him. September 11 will decide more than who the Democratic nominee for Congress will be. It could also create a political figure who could make Menino sweat.