ALBANY — Mayor Bloomberg’s effort to radically overhaul the city’s taxi system by putting 30,000 more cabs on the streets of the outer boroughs was in doubt last night as the GOP-controlled Senate considered killing the measure.

The proposal swiftly passed the Democrat-controlled Assembly, 112-28, earlier in the day.

But yellow-cab owners and drivers, 300 of whom surrounded the Capitol with their taxis in protest, claimed Bloomberg’s plan would destroy their industry by creating cutthroat competition for fares and devaluing existing taxi medallions.

“We can’t afford it,” Mohammed Kamnaksh said of Bloomberg’s plan as he poked his head out of his cab’s window after making what would have been a $300 trip to Albany.