Retiring House Armed Services Chairman Howard “Buck” McKeon, R-Calif., has made transparency a hallmark of the National Defense Authorization Act process during his brief tenure at the helm of the committee.

Shortly after taking the gavel in 2011, McKeon announced that full text of the legislation would be available online in advance of subcommittee and full committee meetings. The House NDAA markup has been largely open to press, public and lobbyists. Debate and votes can be watched online, with rare exceptions for classified matters.

Meanwhile, Senate Armed Services Chairman Carl Levin, D-Mich., has largely resisted calls to open his markups since taking the gavel in 2007. With the exception of a two-hour session on sexual-assault provisions in 2013, the full committee has done its business behind closed doors.

The Standing Committee of Correspondents for the daily press galleries continues to push the retiring Senate chairman for transparency, but Levin appears unlikely to budge.

The fiscal 2015 defense authorization will be his last, and though half of the panel’s subcommittees opened their doors last year, “time consuming security procedures preclude us from going back and forth from open session to closed session” whenever classified issues are raised in the full committee markup, he wrote in a Jan. 8 response to an earlier Standing Committee request to open the markup.

The reporters call Levin’s claim “unfounded” in a response of their own, a Jan. 10 letter that is the latest volley in an ongoing exchange.

“The overwhelming majority of issues discussed in authorization markups are not classified,” wrote outgoing Standing Committee Chairman David Lightman, a veteran Washington correspondent for McClatchy Newspapers.

Lightman, who handed off his gavel on Wednesday, pointed out that the House Armed Services Committee “in marking up its very version of the very same bill as yours every year” has not experienced any difficulties navigating classified data “according to reporters who have covered both panels for nearly two decades.”

John Donnelly, who writes about defense policy for CQ Roll Call and has covered the issue in Congress since 1995, is one of the chief proponents of more transparency in the Senate markups. Donnelly serves as secretary of the Standing Committee; his term also ended on Wednesday.

Though “sunshine” rules mandate that Senate panels open their markup proceedings, committees can close their doors on the basis of certain exceptions if a majority of members vote to do so. One exception, cited by Levin, permits committees to shut out the public, press and lobbyists when discussions “will disclose matters necessary to be kept secret in the interests of national defense.”

For the fiscal 2014 bill, senators voted 20-6 to conduct full committee markups in closed session. Democrats Claire McCaskill of Missouri, Jeanne Shaheen of New Hampshire, Kirsten Gillibrand of New York and Richard Blumenthal of Connecticut were joined by Republicans Mike Lee of Utah and Ted Cruz of Texas in voting against the closed sessions.

McCaskill has been a stalwart for transparency on the committee. Republicans Kelly Ayotte of New Hampshire, John McCain of Arizona and David Vitter of Louisiana have joined the opposition, but all three voted to conduct the markup proceedings behind closed doors in 2013.

The strongest support for transparency from lawmakers came in 2010 and 2011. In each of those years, nine senators voted to keep the doors to the full committee markup open, but they were still a minority.

Levin does not intend to respond to the Standing Committee’s most recent letter, according to spokeswoman Tara Andringa.