Sen. Ed Murray, D-Seattle, has proposed a bill to fund a $766 million expansion of the state convention center in downtown Seattle.

The money would not come from the state general fund, which faces a $6 billion shortfall, but from an existing hotel tax of 7 percent on hotel bills in Seattle (and 2.8 percent in the rest of King County.)

The expansion would double the convention center's exhibit space. Washington State Convention and Trade Center officials say it would allow them to book more national conventions that are now going to other cities.

But is it really a wise use of tax money?

As I reported last month, the convention center has actually seen lower attendance in recent years than it did before its last major expansion.

And recently, the WSCTC posted its fiscal 2008 numbers, which reveal a big decline in out-of-state convention attendees. The center drew 130,000 to national conventions last year, the lowest number since 2002. Attracting those out-of-state visitors is the center's primary goal because they bring new spending to the state. (The center reported a record year in attendance at local meetings and events, drawing more than 350,000.)

Convention centers across the country have had trouble filling their space. A report for the Brookings Institution in 2005 argued there is an oversupply of convention space that is only getting worse as cities continue to outdo one another with bigger convention halls.

But convention center backers believe they can beat the national trend because Seattle remains a desirable destination. Even with the proposed expansion, Seattle's center would remain small compared with many other cities.

Murray said he views the WSCTC as a success story, pointing to its role in revitalizing downtown.

"To those of us who think back to what the downtown core was like before it was there, it has been a big plus," he said.

He said construction work on the expansion could get started as early as next year, creating jobs in a troubled economy.

But Rep. Ross Hunter, D-Medina, chairman of the House Finance Committee, said he has doubts about the convention center's financial projections, which he called "too precious to believe."

Those projections estimate that there is just enough hotel tax money to pay for the convention center expansion (with a little left over for a KeyArena renovation sought by Seattle Mayor Greg Nickels). There would be none left over for lawmakers to use for other purposes.

That would very conveniently stop the Legislature from tapping the taxes for other purposes, as lawmakers did last year when they grabbed a $65 million surplus from the convention center account and spent it on the state general fund and low-income housing.

Hunter said he agrees the state shouldn't get in the habit of diverting the center's local tax money for state programs. But he wants to see more detailed plans from the convention center before okaying such a major project.

No public hearing has been scheduled yet on Murray's bill, which was referred to the Senate Ways & Means Committee.