Merrick Garland, Biden's pick for attorney general, could face tricky political questions during his confirmation hearing before the Senate Judiciary Committee today. In the wake of the Jan. 6 attack on the Capitol, Garland and Democrats are expected to point to Garland's work prosecuting the Oklahoma City bombing as evidence of his ability to investigate and prosecute domestic terrorism.

"If confirmed, I will supervise the prosecution of white supremacists and others who stormed the Capitol on January 6 – a heinous attack that sought to disrupt a cornerstone of our democracy: the peaceful transfer of power to a newly elected government,” Garland will say.

Garland's opening statement also conveys a commitment to equity, saying that upholding the Civil Rights Act remains "urgent" for the Department of Justice. Garland has received ample bipartisan support, ahead of his confirmation hearings before Senate Judiciary Monday and Tuesday, 61 former federal judges and a bipartisan group of more than 150 former Justice Department officials have penned letters in support of Garland's confirmation.

-ABC News' Alexander Mallin and Benjamin Siegel

Three of Biden's picks for key administration positions have hearings before Senate committees Tuesday.

The Senate Energy and Natural Resources Committee will hold a hearing to consider Debra Haaland for secretary of the Interior. If the Senate confirms her as secretary of the interior, Haaland would be the first Native American to serve in a presidential Cabinet and would be the first Native person to oversee an agency that's played a major role historically in the forced relocation and oppression of Indigenous people.

The Senate Health, Education, Labor and Pension Committee will consider Xavier Becerra to serve as secretary of health and human services.

Republican opposition to Becerra has been mounting since Biden announced his nomination in December. On Monday, a group of Republican lawmakers penned a letter to Biden urging him to withdraw Becerra's nomination.

The group of lawmakers, including 11 senators and many more members of the House, argued that Becerra is inexperienced and ill-prepared to guide the agency. Democrats have argued that Becerra has extensive experience in health care policy, first as a congressman who oversaw components of Medicare and then as a defendant of Obamacare as attorney general, using that role to add new focus on the issue.

And the Senate Judiciary Committee will resume its hearing, which began Monday, to consider Merrick Garland for attorney general.

Garland received a fairly warm welcome from both sides of the aisle during Monday's hearing, and a few GOP senators expressed their support for Garland. In the first half of his confirmation hearing Monday, he told senators his first briefing once he takes office at the Justice Department will be on the Jan. 6 assault on the U.S. Capitol.

-ABC News' Cheyenne Haslett, Allison Pecorin, Luke Barr and Alexander Mallin