WASHINGTON – Armed with charts, video presentations, hired consultants and military experts, New England lawmakers are gearing up to persuade an independent commission that the region’s Navy, Army and Air Force bases are worth keeping open.

The key forum will be a hearing Wednesday before four members of the Base Closure and Realignment Commission, which will spend the day in Boston to take testimony on an issue that could drastically change the landscape of the military presence in New England.

Lawmakers and defense analysts consider it a long shot at being able to reverse the recent proposed realignment, which could cost New England three bases and nearly half of the jobs to be lost through base closures nationwide. But at least one base could have a chance of being saved: the submarine base in Groton, Conn.

“It is a very critical moment. It is the day when you arrive in court and lay before the judge the elements and facts of the case,” said Robert Gilcash, military analyst with McKenna Long Aldridge in Washington.

The main argument, lawmakers say, will be their base’s military value – a key component considered by the Pentagon in deciding what bases should be on the list. Officials have questioned the Pentagon’s scoring, including what military assets were included and how much each was worth.

In a letter to Defense Secretary Donald Rumsfeld last week, BRAC Chairman Anthony Principi asked for more information on why the Pentagon chose to close Portsmouth rather than the Pearl Harbor shipyard.

Sen. Olympia Snowe, R-Maine, took that as a positive sign, saying it will give a boost to the state’s arguments that Portsmouth is the most efficient shipyard, and shifting work to the other three yards will create backlogs and hurt Naval operations.

But she said it won’t be easy.

“It’s hard to get into their heads,” she said. “We just have to make sure that we’re giving them all the data, and where the Defense Department has deviated from the criteria, and hope the commission agrees.”

At Wednesday’s hearing, officials from Connecticut, New Hampshire and Maine will each get two hours to make a presentation to the commission, while Massachusetts will get one hour and Rhode Island – which escaped nearly unscathed – will get 30 minutes.