Washington (CNN) — As Democrats in Congress celebrate a historic number of women elected to their ranks, the White House’s top ranks reflect a very different picture — one that is largely male.

CNN has learned President Barack Obama is expected to nominate White House chief of staff Jack Lew as treasury secretary.

The likely contenders to replace Lew — including Ron Klain, who once served as Vice President Joe Biden’s chief of staff, and Denis McDonough, a deputy national security adviser — are all men.

Then there’s the president’s recent choice for defense secretary: former Sen. Chuck Hagel. The preferred choice to replace Hillary Clinton as secretary of state is another man: Massachusetts Sen. John Kerry.

The trend troubles those who study the role of women in government.

Vacancies at Cabinet table

“What you’re hearing is that as new openings come up, there are missed opportunities to bring women in at that level,” said Debbie Walsh, director of Rutgers University’s Center for American Women and Politics, which tracks women in elective office.

“It is concerning at a time when you have a gender gap that put (Obama) over the top, and that gap was a diverse gender gap,” Walsh said.

Susan Rice, the U.S. ambassador to the United Nations, was believed to be the front-runner for Clinton’s job but withdrew her name from consideration. She took heavy criticism from Republicans over her public statements about the deadly attack on the American diplomatic mission in Benghazi, Libya, in September.

Others candidates, such as Michele Flournoy, who served as undersecretary of defense, and Lael Brainard, an undersecretary at the Treasury Department, were bypassed in favor of Hagel and Lew, respectively.

Moreover, there are more men than women among names being considered for other Cabinet positions in Obama’s second term.

The White House stresses a commitment to diversity and points to a number of women named to big jobs led by Clinton, Labor Secretary Hilda Solis, Homeland Security Secretary Janet Napolitano and Health Secretary Kathleen Sebelius.

Solis on Wednesday resigned from her position and is expected to leave the department around Obama’s inauguration later this month.

But the administration is looking for a woman to fill the commerce secretary position, two sources familiar with the nomination told CNN. Rebecca Blank is acting commerce secretary but is not expected to be the permanent choice.

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The administration also says that more than half of the White House staff is made up of women, many in key senior leadership roles.