Capitol Hill’s busy day: Confirmation hearings, updates on the Russian hacking attack and more.

It was a busy day on Capitol Hill.

President Biden’s nominees for interior and health secretary appeared before Senate committees, where they faced tough questions from Republicans.

The two-day confirmation hearing of Representative Deb Haaland, the nominee for interior secretary, by the Energy and Natural Resources committee, kicked off at 9:30 a.m. Eastern, and questioning by Republicans on the panel was expected to be particularly tough. Democrats have pointed to the historic nature of her nomination: She would be the first Native American serve in the cabinet, leading a department that plays a huge role providing services to 1.9 million Indigenous people and helping maintain the government’s relationship with 574 federally recognized tribes. Her detractors have zeroed in on her opposition to all oil and gas exploration on public land and to the natural gas extraction method known as hydraulic fracturing, or fracking.

Xavier Becerra, the California attorney general and nominee to lead the Department of Health and Human Services, appeared before the Health, Education, Labor and Pensions committee at 10 a.m. He would be the first Latino to serve as health secretary, and has deep experience as a lawmaker and in legal defense of the Affordable Care Act. But Republicans have painted him as an extremist, faulting him for his views on the A.C.A. and abortion rights. He is scheduled to appear before the Senate Finance Committee on Wednesday.

The full Senate voted to confirm Mr. Biden’s nominee for ambassador to the United Nations, Linda Thomas-Greenfield, and the nominee for agriculture secretary, Thomas J. Vilsack.

Two other Senate committees began investigative hearings into the security breakdowns that failed to prevent the Jan. 6 riot at the Capitol. The joint hearing of the Homeland Security and Governmental Affairs Committee and the Rules and Administration Committee started at 10 a.m. It was the first time the public heard from top security officials at the time of the assault.

Jerome H. Powell, the Federal Reserve chair, appeared before the Senate Banking Committee on Tuesday, and is slated to testify before the House Financial Services Committee on Wednesday. His testimony comes as Democrats look to pass $1.9 trillion in new economic relief, an effort that has raised concerns in some quarters about the potential for higher inflation. Mr. Powell has typically pushed for additional government support to help the economy through the pandemic.

Vaccine makers also appeared before the House Energy Committee to discuss expanding availability of their products. Executives from Pfizer, Moderna, Johnson & Johnson, AstraZeneca and Novavax were scheduled to appear.

The confirmation hearings for the attorney general nominee, Judge Merrick B. Garland, entered their second day on Tuesday, with lawmakers hearing from with expert witnesses. During his appearance before the Senate Judiciary Committee on Monday, Judge Garland vowed to make the federal investigation into the Capitol riot his first priority if confirmed.

The Senate Intelligence Committee began a hearing on digital security at 2:30 p.m., with top executives from the tech companies FireEye, SolarWinds, Microsoft and CrowdStrike appearing as witnesses. The top cybersecurity official at the White House said last week that investigators were still uncovering details of a broad Russian breach of government and corporate computers discovered late last year, which became known as the SolarWinds attack. Officials believe that a Russian intelligence operation inserted code into network management software made by SolarWinds, a Texas company, and other layers of the supply chain to infiltrate government agencies.