Becerra, Biden’s pick for health secretary, is expected to face tough questions from Senate Republicans.

President Biden’s nominee for health secretary, Xavier Becerra, will appear before a Senate committee Tuesday morning, where he is expected to face tough questions from Republicans who are trying to paint him as an extremist and to use his confirmation as a political cudgel against Democrats up for re-election in 2022.

If confirmed, he will immediately face a daunting task in leading the department at a critical moment, during a pandemic that has claimed half a million lives and taken a particularly devastating toll on people of color. He would be the first Latino to serve as secretary of the federal Department of Health and Human Services.

Mr. Becerra, a former member of Congress who is now attorney general of California, lacks direct experience as a health professional. But he took a deep interest in health policy while in Washington, and has more recently been at the forefront of legal efforts on health care, leading 20 states and the District of Columbia in a campaign to protect the Affordable Care Act from being dismantled by Republicans.

Republicans and their allies in the conservative and anti-abortion movements have seized on Mr. Becerra’s defense of the A.C.A. as well as his support for abortion rights. Senator Tom Cotton, Republican of Arkansas, took to Twitter on Monday, where he branded Mr. Becerra an “unqualified radical” in a post that featured a political advertisement targeting Democrats who support Mr. Becerra’s confirmation.

“Any Senator supporting him will pay a price with voters,” Mr. Cotton wrote.

The Conservative Action Project, an advocacy group, issued a statement on Monday signed by dozens of conservative leaders, including several former members of Congress, complaining that Mr. Becerra had a “troubling record” with respect to “policies relating to the sanctity of life, human dignity and religious liberty.”

They cited in particular his vote against banning “late-term abortion,” and accused him of using his role as attorney general “to tip the scales in favor of Planned Parenthood,” a group that advocates abortion rights.

Democrats are emphasizing Mr. Becerra’s experience leading one of the nation’s largest justice departments through an especially trying period. In a statement, Senator Patty Murray, who will preside over Tuesday’s hearing as chairwoman of the Senate health committee, said Mr. Becerra had “proven himself as an executive leader” and spotlighted his commitment to social justice.

“He has held companies accountable for flouting Covid-19 safety rules and putting workers at risk,” Ms. Murray said. And, she added, “he has worked throughout his career to advocate on behalf of communities of color across health, immigration, education and more.”

Heading into Tuesday’s hearing, Mr. Becerra has been making the rounds on Capitol Hill; as of Monday he had met with at least 40 senators. Andrew Bates, a spokesman for the Biden transition, called him a “tested, qualified leader” who has “decades of health policy experience,” including “a strong record of fighting to lower costs for patients.”

Tuesday’s session will be the first of two confirmation hearings held this week by the Senate Committee on Health, Education, Labor and Pensions. On Thursday, the panel will consider the nominations of Dr. Vivek Murthy for surgeon general and Dr. Rachel Levine for assistant secretary of health.

If the Senate approves, Dr. Murthy would reprise his role as surgeon general under former President Barack Obama, and Dr. Levine would become the first openly transgender official to win Senate confirmation.