Joe Biden is considering retired four-star general Lloyd Austin as his nominee for Defense secretary, adding him to a shortlist that includes Jeh Johnson, Tammy Duckworth and Michele Flournoy, two sources with direct knowledge of the decision-making tell Axios.

Why it matters: A nominee for Pentagon chief was noticeably absent when the president-elect rolled out his national security team Tuesday. Flournoy had been widely seen as the likely pick, but Axios is told other factors — race, experience, Biden's comfort level — have come into play.

Between the lines: Biden's top advisers feel pressure to announce an African-American to a prominent Cabinet role. Earlier this week, Rep. Jim Clyburn (D-S.C.), a top ally, said he was disappointed more African-Americans had not been included in Biden's early selections.

• Austin would be the first Black secretary of Defense in American history.
• The former head of U.S. Central Command, Austin retired from the Army in 2016. He would need a congressional waiver to serve, just as President Trump's first Defense secretary, James Mattis, required as a recent military retiree.
• Flournoy was never a foregone conclusion for secretary despite some media reporting suggesting the job was already hers.
• The president-elect does not have the same deep, long-term relationship with her as he does, for example, with Tony Blinken, Flournoy's former business partner and Biden's nominee for secretary of State.

But, but, but: Flournoy, a former top Pentagon official, remains in contention, as do Johnson, a former Homeland Security secretary, and Duckworth, an Illinois senator and combat veteran of the Iraq War.

• Johnson, who served as the Pentagon's general counsel in the early years of the Obama administration, is also in contention for attorney general, sources tell Axios.
• Biden had considered Duckworth as his running mate.

Behind the scenes: When the president-elect omitted a candidate for secretary of Defense from his marquee national security rollout, it raised questions about whether there were problems with Flournoy's nomination or a late-blooming candidate had eclipsed her.

The big picture: The Biden team wants to elevate diplomacy and de-emphasize the military as an instrument of national power.

• "So having DoD rollout front-and-center sends one message," said a source close to Biden. "Not doing so sends another message. There has always been the intent to signal from Day One that this is not an administration that is going to put the Pentagon at the center of things."
• Biden said Tuesday: "This team meets this moment. They embody my core belief that America is strongest when it works with its allies."