A draft request for assistance between FEMA and the Department of Defense is under discussion that would seek as many as 10,000 service members to support administering COVID-19 vaccine shots up to 100 sites nationwide, according to a FEMA official.

A defense official, who spoke on condition of anonymity, confirmed discussions are underway, but the final number of personnel is not settled.

-ABC News' Matthew Vann and Luis Martinez

Newly confirmed Secretary of State Antony Blinken held a press briefing at the State Department Wednesday during his first full day on the job.

Blinken announced that he will bring back daily press briefings at the State Department, calling a free press a "cornerstone" of democracy. His predecessor, former Secretary Mike Pompeo, had a more standoffish relationship with the media. Blinken promised to be "forthright" with the press and treat the media with respect.

He took questions but said that many of the State Department's policies are under "review."

"This is my first full day on the job as secretary of state and to restate what I said before, it is a deep honor to be in this job, and I'm gratified that president sees fit to entrust me with this responsibility," Blinken said. "And I'm incredibly excited about the work ahead, especially working with the men and women of the State Department to try to serve the American people and represent our country to the world."

The Senate Veterans' Affairs Committee is holding a confirmation hearing for Biden's Cabinet nominee Denis McDonough to serve as veterans affairs secretary.

"Though only a small percentage of Americans have served in our armed forces, the president has called on every American to embrace our responsibility to support our veterans and their families," McDonough said in his opening statement, noting that he is not a veteran but has witnessed their service, which he praised.

In addition to helping to get veterans through the pandemic, McDonough said he would focus on what he described as the department’s three core responsibilities: providing the best health care, ensuring timely access to benefits and “honoring our veterans with their final resting place.”

Sen. Amy Klobuchar, D-Minn., introduced McDonough to the committee as an "adept manager who understands how to tackle complex challenges throughout our government," adding, "He will listen, then he will get things done for you."

McDonough, 51, who served as former President Barack Obama's chief of staff in his second term, was previously Obama's principal deputy national security adviser, including during the 2011 Navy SEAL raid that killed Osama bin Laden. Like Biden's Secretary of State Antony Blinken, McDonough is in the famous Situation Room photo.

Prior to his eight-year White House tenure, McDonough served in senior leadership and policy-making positions in both chambers of Congress.

He's credited with helping Obama bridge divides on Capitol Hill, including gaining support for the Veterans Choice Act, which former President Donald Trump later signed into law.

Biden is continuing his calls with world leaders and spoke with Japanese Prime Minister Yoshihide Suga Wednesday morning.

The two world leaders spoke about renewing the U.S. commitment to Article 5 of NATO, regional security issues -- particularly with regard to China -- and the need to denuclearize the Korean peninsula, according to a White House readout.

The pair also spoke about working together on COVID-19 as well as a desire to address climate change. Biden has also had calls with leaders of Mexico, Canada, the United Kingdom, France, Germany and Russia.

-ABC News' Moly Nagle