Biden signed an executive order Wednesday that will begin a 100-day investigation into vulnerabilities in the supply chain of critical sectors including computer chips, large capacity batteries, active pharmaceutical ingredients and critical and strategic materials, including rare earth minerals.

Biden touted the move as something that will strengthen America for future challenges like the COVID-19 pandemic, which revealed myriad flaws in the supply chain.

"This is about making sure the United States can meet every challenge we face in this new era," Biden said. "Pandemics, but also in defense, cybersecurity, climate change, and so much more. And the best way to do that is by protecting and sharpening America’s competitive edge by investing here at home."

In remarks before the signing, he called the subject one of few "where Republicans and Democrats agreed," having met earlier in the day with a bipartisan group of lawmakers.

Sen. Richard Shelby, R-Ala., a top Republican on the Appropriations Committee, is throwing his weight behind an alternative nominee to head the Office of Management and Budget: Shalanda Young.

Young was nominated by Biden to be deputy director of the Office of Management and Budget. Young was most recently the staff director at House Appropriations, and she and Shelby have a close working relationship.

“I believe she would be good in that role. She’s smart, she knows the process inside-out, and she’s an honest broker who has demonstrated the ability to work with both sides and get things done. She would have my support, and I suspect many of my Republican colleagues would support her, as well," Shelby said in a statement. "But that’s up to the Biden Administration.”

White House press secretary Jen Psaki was asked about Shelby's support on Wednesday and the possibility of Young being a Neera Tanden replacement, but she made clear that the White House maintains support for Tanden.

-ABC News' Trish Turner

Energy and Natural Resources Committee Chairman Sen. Joe Manchin, D-W.V., will vote to confirm Rep. Deb Haaland's, D-Ariz., nomination to serve as secretary of the interior, easing concerns that Haaland's appointment could be in jeopardy.

Manchin has been in close focus on this and other nominations this week, as the moderate Democrat has significant ability to jeopardize nominees in the evenly divided Senate.

Manchin has said he will oppose the nomination of Neera Tanden to the Office of Management and Budget and has not committed to a position on Xavier Becerra's nomination to lead the Department of Health and Human Services.

"I believe that every Presidential nominee and every Member of Congress must be committed to a new era of bipartisanship. That is the standard the overwhelming majority of Americans expect and deserve," Manchin said in a statement. "With respect to Representative Haaland and her confirmation hearing, while we do not agree on every issue, she reaffirmed her strong commitment to bipartisanship, addressing the diverse needs of our country and maintaining our nation’s energy independence."

-ABC News' Allison Pecorin

Biden has officially extended the national emergency declared over the COVID-19 pandemic beyond March 1. By law, the national emergency would have ended a year after it was declared unless the president took action within 90 days of the expiration date.

"The COVID-19 pandemic continues to cause significant risk to the public health and safety of the Nation," Biden wrote in his letter to Congress. "More than 500,000 people in this Nation have perished from the disease, and it is essential to continue to combat and respond to COVID-19 with the full capacity and capability of the Federal Government."

The national emergency was initially ordered by former President Donald Trump on March 13, 2020, freeing up financial resources for the country as the pandemic took hold.

-ABC News' Molly Nagle

Garland described the Jan. 6 insurrection at the Capitol as "the most heinous attack on the democratic processes I have ever seen and one I never expected to see in my lifetime." He added he will make sure to provide career prosecutors all the resources they need to carry out their investigations while also taking a broader look at the symptoms behind the country's domestic extremism problem.

Asked by Sen. Dianne Feinstein, D-Calif., whether the president "has the absolute right to do what he wants with the Justice Department," Garland said presidents are "constrained by the Constitution as are all government officials" and cited comments by Biden committing to not interfere with Justice Department matters. At the same time, Garland said that the Department of Justice is part of the executive branch and because of that, on policy matters they do "follow the lead of the president and the administration as long as it is consistent with the law." When asked who an attorney general represents when his interests conflict with the president's, Garland said the attorney general "represents the public interest, particularly and specifically as defined by the Constitution and the statutes of the United States."

Asked whether the president can order an attorney general to open or close an investigation, Garland said such a question was a hard one for constitutional law but that he did not expect it to be a question for himself given President Biden's statements assuring independence for the department.

Sen. Lindsey Graham, R-S.C., took a contentious tone with Garland in his line of questioning as he pressed him on multiple topics. At one point, when Graham asked Garland whether he thought former FBI Director Comey was a good FBI director, Garland declined to answer, which Graham said he found "stunning" because he thought Comey was terrible. Sen. Sheldon Whitehouse, D-R.I., pressed Garland on whether he would commit to investigating not only the rioters who attacked the Capitol on Jan. 6, but those "upstream" like the funders, organizers, ringleaders or others not actually at the Capitol.  Garland cited his past experience as a line prosecutor, noting "we begin with the people on the ground and we work our way up to those who are involved and further involved -- and we will pursue these leads wherever they take us."

Asked about whether he would end the Trump Justice Department's policy of generally stonewalling in the face of oversight requests from Congress, Garland committed to Whitehouse that the department would be "as responsive as possible" to any requests and "at the very least why if it can't answer a question or can't answer a letter." Garland also committed that he would work with Whitehouse on getting answers to the committee on requests that the Justice Department under Attorneys General Bill Barr and Jeff Sessions previously ignored.

In an exchange with Sen. John Cornyn, R-Texas, Garland committed that his personal politics will have no impact on prosecutions and investigations he oversees as attorney general. Asked what he would do if he was ordered to do something that he considered to be unlawful, Garland said he would first tell the president or whoever else was asking him that what they were ordering was unlawful and would resign if no alternative was accepted.

Asked by Sen. Amy Klobuchar, D-Minn., what he will do to improve morale in the department, Garland said he would on his first day make an oath to career prosecutors and agents "that my job is to protect them from partisan or other improper motives." Klobuchar then asked Garland whether he believes he'd need "additional authorities" to combat the country's domestic terrorism problem. Garland said while the department "is probably always looking for new tools ... the first thing we have to do is figure out whether the tools that we have are sufficient."

-ABC News' Alexander Mallin