The Maryland senator whose district includes National Harbor on Wednesday blasted a plan to steer a billion-dollar casino there, saying the move smacked of the kind of “backroom deals” that Prince George’s County needs to move beyond.

C. Anthony Muse (D-Prince George’s) told fellow senators at a legislative hearing in Annapolis that he considered the casino plan offered last week by Prince George’s County Executive Rushern L. Baker III (D) to be “an assault on local courtesy” and vowed to defeat state legislation needed to make it happen.

“I object to the way this deal was done and will do everything in my power to stop the legislation,” Muse told the Senate Budget and Taxation Committee during a lengthy hearing on a bill to authorize a sixth casino in Maryland.

Muse’s objection — and concerns raised Wednesday by the county council member who represents the area — further complicates the outlook for the legislation during the 90-day session.

The idea of a Prince George’s venue is already opposed by the owner of a casino scheduled to open in June in neighboring Anne Arundel County. An analysis released Wednesday by nonpartisan legislative staff concluded that the Anne Arundel casino and one planned for downtown Baltimore could lose about 10 percent of their slot business if another opens in Prince George’s.

As drafted, the new bill would seek competitive bids for a gaming venue in a swath in western Prince George’s that includes both National Harbor, a 300-acre development on the Potomac River, and Rosecroft Raceway, the recently reopened horse track in Fort Washington.

Baker upended the debate last week by endorsing the National Harbor site — a stance he reiterated Wednesday, saying his preference is “the only one that makes sense for us.”

“I know this is a very contentious issue in a very contentious time,” Baker told the Senate committee, as he argued that his plan would bring in revenue for both the state and the county while generating much-needed jobs and economic development.

Muse, who is seeking the Democratic nomination for U.S. Senate, argued that the legislation could wait a year, giving officials more time to gauge community reaction to both sites.

Milton V. Peterson, the developer of National Harbor, also appeared Wednesday to endorse Baker’s plan to put a “high-end” casino at the site, which already includes retail, restaurants and hotels.

Peterson pledged to build a “stately” casino and said he had resisted hosting gambling at the site in the past because the plans were not so grand. The legislation being considered would allow Las Vegas-style table games in addition to slot machines, which have been authorized in five other sites in Maryland.

“Under no circumstances would we accept a slots barn,” Peterson said.

If the legislation advances, it is likely to retain a provision inviting competition. Under current law, a state panel is charged with picking Maryland’s slots operators. Both sponsors of the bill, Sen. Douglas J.J. Peters (D-Prince George’s), and Senate President Thomas V. Mike Miller Jr. (D-Calvert) have said they favor allowing bidders for multiple Prince George’s locations.

But the new owner of Rosecroft, Penn National Gaming, suggested that Baker’s pronouncement last week has undermined the process.

Steven Snyder, a senior vice president for the company, testified that “we cannot be disadvantaged from the get-go as Mr. Baker has done to us at Rosecroft.”

Snyder said Rosecroft remains a viable option, and argued that a $300 million casino could be opened there without changing the one-third share of proceeds that Maryland allows slots operators to keep.

Prince George’s officials have said the state would have to provide a more generous deal to an operator at National Harbor so that it could afford to finance a $1 billion project. The exact terms have not been specified by Baker or his aides.

The Senate panel also heard a pitch Wednesday to expand the Peters bill to allow a bid from yet another location: the Boulevard at the Capital Centre in Largo. Representatives of RMD Holdings floated that idea.

The hearing drew several labor union leaders who said they favor a Prince George’s casino because of the jobs it could generate. Several people who reside near National Harbor testified against the idea, including Forest Heights Mayor Jacqueline E. Goodall, who said she was caught off guard by Baker’s idea.

Prince George’s Council member Obie Patterson (D-Fort Washington) also aired several concerns. He said the Peters bill doesn’t include enough funding to mitigate the impact of a casino on the surrounding area.

“At the end of the day, the locals are the ones who are going to get kicked in the hips,” Patterson said.

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