Gov. Rod Blagojevich raised the stakes in the political battle over funding Chicago-area mass transit, saying he would only endorse a sales-tax increase lawmakers sent him Thursday if they also agree to give senior citizens free rides on local trains and buses.

Cornered by fellow Democrats after nearly a year of maneuvering on both sides, Blagojevich made the brand new demand as he sought to soften the political damage of breaking his long-held vow to veto a sales tax increase.