Former Defense Undersecretary for Policy Michele Flournoy prepares to testify during the House Foreign Affairs Committee hearing on "NATO at 70: An Indispensable Alliance" on Wednesday, March 13, 2019.

WASHINGTON — Michele Flournoy, Joe Biden's probable pick to run the Pentagon, would be the first female secretary of defense if confirmed and could appoint an unprecedented number of women to senior roles at the Defense Department. But she could also face resistance from progressive Democrats for what they see as her hawkishness and her ties to the defense industry.

Biden is poised to announce Flournoy as his nominee as early as Tuesday, according to three people familiar with the decision. Throughout her long career in national security, she has built an infrastructure of female colleagues and friends, many of whom regard her as a mentor in a field still dominated by men. The Biden-Harris Pentagon agency review team, a transition task force that is more than 50 percent female, includes some of those women who could now fill top jobs.