Just hours after federal officials awarded the city $354.5 million in federal funds to help finance a pay-to-drive-in-Manhattan scheme, the speaker of the Assembly, Sheldon Silver, yesterday warned that Mayor Bloomberg’s congestion pricing proposal had high hurdles to clear.

The federal dollars announced yesterday are contingent upon the state Legislature voting to implement a fee to drive into Manhattan, or an alternative proposal that would achieve the same traffic-reduction goals, by next March.

“You can reduce traffic by 6.3% by stopping trucks from coming into the city on Wednesdays,” Mr. Silver, a Democrat, said at a press conference in his Lower Manhattan office, during which he voiced “major concerns” about congestion pricing. Mr. Bloomberg has proposed charging cars $8 and trucks $21 to enter Manhattan south of 86th Street during peak hours.

The U.S. Secretary of Transportation, Mary Peters, said yesterday that while the details of Mr. Bloomberg’s plan could be tweaked, it was unlikely that the traffic reduction goals set out by the city could be achieved without charging drivers to enter most of Manhattan.

New York will receive $1.6 million immediately under the federal plan. The rest of the money will arrive in March if the State Legislature acts on the recommendations of a 17-member congestion pricing commission by then.

Mr. Silver said he would make his three appointments to the congestion pricing panel, which will study Mr. Bloomberg’s proposal, as well as some alternative plans, in the next few days.

When asked if he thought the commission would recommend the city’s congestion pricing plan, Mr. Silver said he imagined it would “come up with something that’s Solomon-like in its conclusions.”

While New York City is in line to receive less than the $537 million Mayor Bloomberg had asked for, city officials hailed the announcement as a victory against New York’s notorious traffic jams and a major boost for the passage of congestion pricing that a few weeks ago seemed all but dead.

Under the plans announced by the transportation secretary, the Bush administration has earmarked $112 million to pay for rapid bus corridors, where traffic lights would be timed on special lanes to allow buses to drive through the city without stopping at red lights.

The Metropolitan Transportation Authority would receive $184 million for capital and operational investments under the rubric and $10.4 million is allocated to pay for congestion pricing infrastructure, including cameras and E-ZPass technology. The city would also receive $29.3 million for pedestrian and traffic signal improvements, and $15.8 million would pay for an expanded ferry system.