Gov. Charlie Baker is halting the $1 billion plan to expand the Boston Convention & Exhibition Center, and replacing more than half of the convention center authority’s board amid a variety of concerns of whether the proposal could ever meet its financial promises.

The decision, Baker aides say, will allow the newly remade board to review the plans with fresh eyes — and his budget chief, Kristen Lepore, emphasized that it doesn’t necessarily deal the controversial project a fatal blow.

But it leaves uncertain at best the question of whether the project will ever move forward under the Baker administration, which along with the state treasurer's office, has to sign off on the massive bond offering before shovels ever enter the ground.

In a statement, Baker said he was "pausing" the expansion, noting that the "environment has changed greatly" since the project was first proposed five years ago.

"Plunging ahead now, when the data on the expansion’s feasibility is mixed, combined with the change of leadership at the MCCA would be irresponsible given the vast amounts of taxpayer dollars necessary to not only build but operate the expanded facility in the face of pressing financial needs outside of the booming Seaport District," Baker said.

Lepore, speaking with reporters earlier today, ticked off a list of concerns, namely that the South Boston convention center — even before the proposed expansion — has failed to meet the projections of filling hotel rooms. According to Lepore, initial estimates called for the BCEC to generate 670,000 hotel room stays a year, but last fiscal year, the center only accounted for 472,000 room nights — and that’s combined with the Hynes Convention Center downtown.

Lepore also doubted that the expansion plans would push the sprawling complex into the top five of largest convention centers in the country, as the project’s backers have touted. Instead, Lepore said it would leave it as only the 15th largest when counting available exhibition space; it currently is the 24th largest.

The financing for the project also raised red flags. Lepore said the BCEC currently is operating at a loss. Expanding it would only add to those losses, and with the statewide hotel tax included as a backstop in the project’s plans, it could suck cash that would otherwise go to state’s general fund, she said.

The decision by convention center chief James Rooney last month to leave to become the CEO of the Greater Boston Chamber of Commerce — after years of guiding the project through the legislature and into its early planning phases — also left the authority with what Lepore called a troubling leadership gap.

In a lengthy statement, Rooney said he's "extremely disappointed" with Baker's decision.

"Obviously we have a new Governor who has his own priorities and who has been met with some difficult challenges during the early days of his term. I have to respect this context," Rooney said, though he argued it's a good time to move ahead with the massive project.

"This decision not only pauses the physical convention center expansion, but also pauses significant economic development, job creation, groundbreaking diversity programs, place-making initiatives in the South Boston Waterfront, and our ability to keep Boston competitive in the global meetings and conventions market," Rooney said. "I would advise the new board and the administration to set a new direction and eliminate uncertainties as quickly as possible."

Today, Baker also announced his nine appointments to the 13-person convention center authority board, two of whom are holdovers from the Patrick administration.

Baker ousted board chair Michelle Antonio Shell, among others, and replaced the members with: Cindy Brown, who will hold a seat designated for the Massachusetts Visitors Industry Council; Andrew Crane, CEO of Crane Construction in Chicopee; Karen Johnson, who manages the analytics division of The Debt Exchange; Amy Latimer, the president of TD Garden; Gregg Lisciotti, a Leominster real estate developer who once served on the MCCA board under Gov. Mitt Romney; John McDonnell, a managing director of the company that makes Tito’s Handmade Vodka; and Frederic Wittman, a Boston-based commercial real estate investor.

Barbara Capuano, the wife of Congressman Michael Capuano, and Paul Sacco, who holds the seat reserved for Massachusetts Lodging Association, will remain on the board as gubernatorial appointees.

The board’s remaining members include Lepore, or her designee; Ronald Rakow, a designee of the Boston’s city CFO and treasurer; and former state Sen. Jack Hart and Michelle Consalvo, both of whom are appointees of the late Mayor Thomas M. Menino.

The various moves by Baker come after he initially slammed the brakes on the $1 billion bond offering in January and ordered a months-long delay as his finance team figured out how to fill a gaping budget deficit.