Charging motorists a fee to enter Manhattan south of 60th Street, and using the money to fund mass transit, is an idea “whose time has come,” Governor Cuomo said two years ago.

Despite that declaration, the Republicans who then controlled the State Senate refused to vote on congestion pricing. The proposal died.

But Democrats took control of the State Senate last month, and they back the idea. So now, supporters of congestion pricing are mobilizing in ways they haven’t before. Here’s how:

Mr. Cuomo is a driving force.

The governor has been criticized for the problems plaguing the subways. He, in turn, has argued that congestion pricing can help pay for improvements. If lawmakers don’t pass congestion pricing, he has said, subway riders might see a fare increase.

The M.T.A. is on board.

Metropolitan Transportation Authority officials are conducting a “listening tour” of state lawmakers, said Kathryn Wylde, the president and chief executive of the Partnership for New York City, a business group. Advocates said lawmakers and their constituents were more likely to support congestion pricing if they learned about how the money would be used.

Campaigns are mobilizing.

At least two groups — Fix Our Transit and #FixTheSubway — are rallying labor, immigrant, business and civic organizations. But opposition exists, and it includes some lawmakers representing suburban residents who rely on cars and would pay more to enter the busiest parts of Manhattan.