The effort to expand the board of the Metropolitan Washington Airports Authority took a step forward Wednesday when a D.C. Council committee held a public hearing on legislation that would create four new board slots, including an additional seat for the District.

The full D.C. Council is expected to take up the bill Tuesday, when it is also expected to vote on the nomination of Barbara Lang, president of the D.C. Chamber of Commerce. Lang was recently nominated by Mayor Vincent C. Gray (D) for the District’s expected new seat on the MWAA board.

Made up of appointees from the District, Maryland, Virginia and the federal government, the MWAA board is overseeing construction of Metro’s new Silver Line, the long-sought rail extension to Dulles International Airport and Loudoun County.

Remaking the composition of the MWAA board has been a priority for some political leaders in the region, particularly in Virginia, where Gov. Robert F. McDonnell (R) has been pushing for more influence on the authority’s board.

Already, Congress and the Virginia General Assembly have passed bills to increase the size of the board to 17 from 13. Now, the District appears poised to act. (Maryland was not a member of the original compact creating MWAA, so it does not have a vote on altering the board’s makeup.)

Lang’s nomination to the board has already drawn fire from some labor groups, who question her commitment to living wage initiatives. They note that she spoke out against a paid sick leave law that was eventually passed by the D.C. Council. At the time, Lang expressed concerns that the law would hurt small businesses.

At the hearing Wednesday, interim D.C. Council Chairman Phil Mendelson (D-At Large) noted Lang’s stance on the paid sick leave law.

In response, Lang said she was a “collaborative person.”

“We have to co-exist in this sandbox together, so the question is ‘How can we sit down and work through these issues?’ ” she said.

Mendelson said he was hopeful the expected vote by the council to expand the MWAA board would put an end to some of the regional rivalries over who has a bigger say in MWAA affairs.

Even if the bill is approved by the full D.C. Council, it’s not clear how long the board’s expansion would remain in place. Rep. Frank R. Wolf (R-Va.), who sponsored the bill in Congress to expand the board’s membership, recently introduced a bill that would shrink the size of the board to nine and give Virginia the majority of the seats.

Mendelson described Wolf’s bill as “a thumb in the eye of the District.”

“Regionalism requires working together,” Mendelson said.

MWAA’s role overseeing construction of the $5.6 billion Silver Line project has made the authority the subject of intense scrutiny. MWAA also operates Reagan National and Dulles International airports and the Dulles Toll Road.

The board has had a difficult summer after revelations that the authority had given no-bid contracts to former board members and hired Mame Reiley to a $180,000 a year job the day after she gave up her MWAA board seat. In addition, an interim federal inspector general’s report criticized the agency for lavish travel and irregularities in how it awarded millions in contracts.

This month, the board began an attempt to repair its troubled image by approving new travel and ethics policies that ban the kinds of practices that led the nation’s top transportation official to label the group “dysfunctional.”

The authority has moved to sever the contracts with former board members and recently announced that Reiley would be leaving her job. The board also announced a deal had been reached in a lawsuit that pitted McDonnell against board member Dennis Martire. McDonnell had attempted to remove Martire, a Virginia representative and labor leader, from the board. Martire sued to block the action. Some officials feared the case could cost MWAA millions in legal fees if it went to trial.

One current MWAA director, Robert Clarke Brown, a federal representative on the board, testified against the expansion measure, calling it a bad piece of legislation and suggesting that the council put off approving the change.