From Massachusetts to Hawaii, Democrats are leaning heavily on their party’s women to retain control of the Senate, which Democrats now control by a razor-thin margin. A record number of Democratic women, including six incumbents, are running for Senate seats - eclipsing by one the 10 that ran in 1992’s “Year of the Woman.’’ The contests come as the political chasm on key social and economic issues widen, and Democrats hope the stark divides will motivate women to go to the polls in droves in November.