The long-delayed expansion of the Jacob K. Javits Center is moving forward again.

The Public Authorities Control Board, made up of three voting members — Governor Pataki; the Senate majority leader, Joseph Bruno, and the speaker of the Assembly, Sheldon Silver — yesterday unanimously approved the $1.7 billion plan to expand the convention center by roughly 1.3 million square feet.

The plan has won the backing of many politicians — including the City Council speaker, Christine Quinn, who represents the district, and Mayor Bloomberg — as well as tourism industry officials, who say they hope an expansion would boost both retail and hotel businesses.

“As a result of today’s vote, we are now well on the way to building a Javits Center that will be an epicenter for the hospitality and tourism industry,” Mr. Pataki said in a statement.

“Today’s action by the Public Authorities Control Board is the result of an extraordinary partnership between the City, the State, and the private sector led by the hospitality industry that allows us to move forward with a project that will mean thousands of jobs in the building, construction, and hospitality industries — jobs for New Yorkers that need them,” Mr. Bloomberg said in a statement.

The sentiment was echoed by the chairman and CEO of Loews Hotels, Jonathan Tisch, who is also chairman of the city’s tourism marketing group, NYC & Company. “Today’s approval shows that our elected officials have a deep understanding of the social and economic benefits that are derived by a strong tourism industry,” he said. “The expansion of Javits and the extension of the no. 7 line … will be the catalyst for additional growth on the West Side.”

“The expansion of the Javits Center is one of the most important things we can do for the economy of this city,” Ms. Quinn said in a statement.

Some say they are skeptical of the promises of improved industry and increased tourism revenue. “It’s a little like going to Las Vegas and putting $1.7 billion — the cost of the expansion — on a roll of the dice,” a professor at the University of Texas who studies convention centers, Heywood Sanders, said.

Mr. Sanders said New York’s disadvantages, such as high hotel prices, may outweigh its advantages, such as its centrality for many industries, causing people to look to convention sites in other cities, or to opt to pay for the commute into the city rather than hotel rooms that can sometimes cost more than a plane ticket.

“It never has generated the type of development it was supposed to,” he said about the center, questioning whether an expansion would help spur development.

Mr. Tisch said the promise of an expanded convention center already has produced increased interest and new business. “We have seen initial demand from groups that historically were too big for [the] existing facility, and we have business on the books already starting in 2010,” he said. “That shows convention organizers and meeting planners are excited about an expanded Javits.”He said the expansion and upgrade of the Javits — including a new hotel and improved access to areas for exhibits and seminars within the center — “allow us to book groups that will generate hundreds of thousands of room-stays.”

Critics of the plan — Senator Schumer has been among them — argue that the expansion is not well thought out, that it is too small and too expensive.The Municipal Art Society, a planning group that opposes the project design and configuration, claims the state did not update its environmental impact statement and is suing the state to halt construction.

Barring any more delays, demolition will begin within the next two months, official groundbreaking is slated for this fall, and the first phase of construction is to be completed by 2010.