Mayor Bloomberg’s congestion pricing plan will be a political test for the speaker of the City Council, Christine Quinn, who now must take on the responsibility of shepherding the proposal through the 51-member council despite anticipated opposition.

Ms. Quinn, who is attempting to position herself as a successor to Mr. Bloomberg, announced her support for the plan before the deal that puts the council on the hook was brokered. Now it falls to her to ensure that the plan is approved in her wing of City Hall. Under a four-way deal announced last week, the City Council will have to approve a home rule message that essentially asks Albany to take the matter up. While the vote will not technically approve the plan to charge drivers for entering parts of Manhattan, many say it will amount to just that.

“It’s an opportunity, and it’s a potential problem,” a professor of public administration at Columbia University, Steven Cohen, said. “It’s an opportunity to show she has the leadership ability to be mayor, to turn things around on this.”

Ms. Quinn’s staff has already begun setting up meetings with individual council members to discuss congestion pricing, a spokeswoman for the speaker, Maria Alvarado, said. The statement could be an indication she recognizes that winning over members may take time.

Even before Mr. Bloomberg unveiled his plan to charge drivers $8 to enter Manhattan below 86th Street on weekdays or $4 to drive within the congestion zone, seven members from Queens, Brooklyn, and Manhattan sponsored a resolution calling on the mayor to oppose the scheme.

Several members are already on the record supporting the plan, while others say they have not yet made up their minds.

A City Council member of Queens who opposes congestion pricing, David Weprin, said he does not think it is Ms. Quinn’s job to ensure the mayor’s plan is approved in the council.

The speaker “said she wasn’t going to use her pulpit to influence members,” Mr. Weprin, a Democrat of Hollis and Jamaica, said yesterday. “I’m going to take her at her word.”

But others, especially those in favor of congestion pricing, seem to be looking to Ms. Quinn to see the plan through.

Ms. Quinn last week made it clear that she was going to take on that role, issuing a statement the same day a deal was reached to create a commission to study the idea.

“I will work closely with my colleagues to address any outstanding concerns regarding PlaNYC,” she said in the statement, referring to the mayor’s overall environmental plan. “I will work with the state, the Bloomberg Administration, environmental and public health advocates, and labor organizations to implement congestion pricing and the overall plan in the best way for all New Yorkers.”

The dean of Baruch College’s School of Public Affairs, David Birdsell, said that although it will be a struggle, he is confident Ms. Quinn can see this through the council. He said members also would be swayed by accommodations for their constituents, most likely in the form of improved public transportation.

“Everyone at the end of the day is likely to be able to show victories for constituents,” he said. “Everyone is going to have something they can walk away with.”