Bill authorizing $1B expansion of Boston convention center sent to Gov. Deval Patrick's desk

State lawmakers sent to Democratic Gov. Deval Patrick's desk on Wednesday a bill authorizing a $1 billion expansion of the Boston Convention and Exhibition Center.

Supporters of the measure tout the proposed expansion of the center, aimed at increasing its operating space by more than 50 percent, as a way for Boston to compete for some of the largest and most lucrative conventions in the world.

"It will allow more events, both national and international, to come to Massachusetts and bring significant economic benefits and opportunities for residents in Massachusetts," said Senate President Therese Murray, D-Plymouth, in a statement following final passage of the bill.

The measure would authorize the state to borrow to finance the approximately 1.3 million-square-foot expansion of the convention center in the South Boston neighborhood. The bonds would be repaid through proceeds from the state's existing 5.7 percent tax on hotel rooms, with no new taxes envisioned. If the state were to fall short on its debt obligations, the bill would allow for the hotel room tax to be raised, but only in the Boston area.

Patrick said Wednesday he supported an expansion of the convention center, which first opened in 1997, while adding that his administration was still reviewing the legislation.

The Boston-based Pioneer Institute, a conservative-leaning think tank, said lawmakers failed to consider the long-term financial implications of the bill, and it urged Patrick to veto it.

"I believe it will saddle the next administration with hundreds of millions of dollars in deficiencies as a result of overly optimistic revenue projections," wrote Greg Sullivan, Pioneer's research director and a former state inspector general, in a letter to the governor.

The projected economic impact of the expansion has been "artificially inflated" by the Massachusetts Convention Center Authority and assumes an annual average increase in the hotel tax that is far above historical norms, Sullivan argued.

Supporters say the proposed expansion would make the facility one of the five largest convention centers in the U.S.