To the naked eye, the Move NY plan hasn't moved an inch in two years, but its backers are more hopeful than ever that the revolutionary traffic proposal—call it Congestion Pricing 2.0—will be approved, perhaps even this spring.

Two recent developments have boosted supporters' already-increasing optimism: The replacement of Assembly Speaker Sheldon Silver by Carl Heastie and the drive to close the Metropolitan Transportation Authority's $15 billion capital-plan deficit. The Move NY plan happens to generate just enough revenue to fund a $15 billion bond issue.

The original congestion pricing plan for the city, advanced by the Bloomberg administration eight years ago, died for lack of support in the state Assembly. But the new version, created by traffic maven Sam Schwartz and supported by major advocacy organizations including the Regional Plan Association, addresses some political liabilities of the Bloomberg plan and improves on its design.

The Move NY plan hinges on its proposed East River bridge tolls, which will draw howls from some motorists but are barrier-free and fiscally efficient, and would rationalize traffic flow in Queens and Brooklyn, experts say. Some business groups favor congestion pricing because it will reduce traffic jams, which cost many businesses more money than tolls would. However, many New Jersey-bound truckers plow through lower Manhattan to avoid tolls that can reach $70 for an 18-wheeler to travel through Staten Island.

Mr. Silver delivered the fatal blow to the Bloomberg plan in 2008 when he declared that the Assembly would not vote on it. The speaker's decision reflected not only his lack of enthusiasm for it but that of the Assembly majority, which is dominated by New York City Democrats. Since then, proponents of Move NY have systematically courted members of the state legislature and say they have been generally receptive—even members who opposed the Bloomberg plan.

"We think that the Assembly is going to be an opportunity, depending on how things play out over the next couple of months," said Regional Plan Association President Tom Wright.

How Mr. Heastie handles Move NY—which backers plan to jump-start with a press conference later this month—is unknown. He could champion it or, more likely, merely take the pulse of his members, as Mr. Silver did. But he could also do something in between, namely, nudge ambivalent or fence-sitting members to endorse the plan, which would toll vehicles heading into congested parts of Manhattan while reducing tolls by $2.50 to $5 on some outer-borough bridges.

Another source of encouragement for the Move NY coalition is the de Blasio administration's embrace of Vision Zero, which aims to eliminate traffic fatalities in the city. The traffic engineers behind Move NY could develop a metric that shows how many lives could be saved by funding safety improvements with congestion-pricing revenue, and by reducing traffic into Manhattan, where an average of 10 people per day are struck by vehicles. Mayor Michael Bloomberg had promoted his plan as an asthma-reducer, but the argument did not seem to resonate. A fair amount of arm-twisting was needed to get the plan narrowly approved by the City Council before it died in Albany.

Mr. Schwartz, better known as Gridlock Sam, has been persuaded to drop from his version a fee on bicycles crossing East River bridges to Manhattan, which he had initially included apparently on the mistaken assumption that it would please then-Brooklyn Borough President Marty Markowitz. Mr. Markowitz is now out of office, but says he was never consulted about a bike fee and would have opposed the idea for the same reason he opposes new vehicular tolls: he views them as a tax on outer-borough drivers.

A lingering uncertainty for Move NY is what position Gov. Andrew Cuomo will take. Backers have kept the governor's staff abreast of the plan but have avoided putting him on the spot before it appears politically safe for him to support it.

One of the Schwartz plan's selling points—but also a source of controversy—is its imposition of tolls on East River crossings that have been free for as long as any current drivers have been taking them. The lack of tolls triggers a phenomenon known as bridge-shopping, whereby motorists on highways designed to transport huge volumes of vehicles exit those roads and descend onto city streets that lead to the Queensborough, Williamsburg, Manhattan and Brooklyn bridges. Those four spans account for more than one million trips each day, while the tolled Midtown Tunnel and Hugh L. Carey (Brooklyn-Battery) Tunnel are underutilized.

The Move NY plan calls for E-ZPass users to pay $5.54 to cross the East River or 60th Street in Manhattan. Cars without E-ZPass would be billed $8 by mail using license plate-reading technology.

Designers of the plan say it would speed traffic in the central business district by 15% to 20%, reduce the number of vehicular trips into the district by 100,000 per year, yet increase the total number of visits by 110,000, thanks to the mass-transit improvements it would fund.