Xavier Becerra, President Biden’s nominee to lead the Department of Health and Human Services, pledged Wednesday to support Medicare Advantage, the increasingly popular private form of the federal insurance system for older Americans — but indicated he had qualms about more generous benefits it offers.

Testifying at a confirmation hearing before the Senate Finance Committee, Becerra said he “will make sure that there is a level playing field” between traditional Medicare and the private-sector version.

He told senators that it is especially important to avoid overpaying private health plans because Medicare is financially fragile, with the trust fund for Medicare-paid hospital services forecast to become insolvent in three years. “We don’t have the dollars to spare and to waste,” Becerra said.

The nominee’s views on how to treat the two forms of Medicare are significant because, in the past decade, the number of Americans 65 and older preferring private health plans has increased substantially. Medicare Advantage covered 24 million people last year — nearly four in 10 of those on the vast government insurance program that began as part of President Lyndon Johnson’s Great Society of the mid-1960s.

For several decades, congressional Democrats and Republicans have sparred over how much private health plans deserve to reimbursed for their Medicare customers. Given the amount paid to the plans in recent years, it has become common for Medicare Advantage to offer vision and dental services. In addition, patients in private Medicare plans often do not need to have spent three nights in a hospital beforehand — as the program’s traditional version requires — to have a nursing home stay covered.

Becerra singled out that uneven coverage for nursing home stays, saying, “Trying to strengthen and improve Medicare, we have to make sure we’re doing oversight and keeping everyone accountable.” Questioning him, Sen. Sherrod Brown (D-Ohio) noted that people in traditional Medicare tend to be older, less healthy and poorer than those in the private plans.

In broader terms, drawing out Becerra’s position on private-sector Medicare was part of an attempt by several committee Republicans to portray him as a proponent of what one called “socialist-type policies” that would eliminate the private insurance industry.

Becerra rebutted such characterizations.

During his two dozen years as a House member from Los Angeles, Becerra supported the idea of a single-payer health-care system, along the lines of Medicare-for-all plans advocated by several Democratic candidates in last year’s presidential primary. Since he was nominated by Biden in early December, Becerra has been consistent in staying on the path to widening access to health coverage that the president favors.

The nominee reiterated the point Wednesday. “I’m here at the pleasure of the president of the United States,” Becerra told committee members. “He’s made it very clear where he is. He wants to build on the Affordable Care Act. That will be my mission to achieve the goals that President Biden put forward.”

Becerra’s appearance before the Senate Finance Committee was the second of his two confirmation hearings, coming a day after he testified before the Senate Health, Education, Labor and Pensions Committee.

HELP has jurisdiction over many issues involving HHS. But the Finance Committee has greater influence over the fate of Becerra’s nomination, voting in the coming days whether to forward his name for the full Senate to consider.

With the smallest possible majority, Senate Democrats appear poised to confirm Biden’s choice to lead HHS. No Democrats have stepped forward to say they will oppose him.

Nevertheless, conservative senators and allies in outside groups are making a vociferous show of portraying Becerra as an unqualified extremist.

Sen. Tom Cotton (R-Ark.) is using his own campaign funds — in the mid-five-figure range, a staffer said — to air ads from Wednesday until the full Senate’s confirmation vote. The ads claim Becerra wants to eliminate job-based health benefits and defended shutdowns during the coronavirus pandemic that have destroyed small businesses and hurt schoolchildren. The ads are airing in New Hampshire and Georgia, where Democratic incumbents are predicted to face tough reelection campaigns.

Among the outside groups, Heritage Action, a grass-roots conservative group, is sponsoring a $600,000 campaign that includes television and digital ads, claiming that Becerra “supports government-run health care” and is “a radical partisan, not a doctor.”

And Tony Perkins, president of the Family Research Council, an antiabortion group, denounced Becerra in stinging terms Wednesday, branding him “a left-wing culture warrior” who “would be a disaster for HHS and a menace to every American who cares about protecting human life and freedom.”

Becerra’s views on religious liberty were a recurrent attack line during Wednesday’s hearing. “It does seem like as attorney general, you spent an inordinate amount of time and effort suing pro-life organizations,” said Sen. John Thune (R-S.D.), one of several GOP senators who accused the nominee of having sued nuns.

Becerra said repeatedly he has never sued nuns. He said his office had sued the Trump administration for making it easier for employers to refrain from providing coverage of birth control required by the ACA if they have objections on religious or moral grounds. That policy change, he said, conflicted with California law.

Republicans persisted. “I’ve got serious concerns with the radical views you’ve taken on abortion,” said Sen. Steve Daines (R-Mont.), in one of the testiest moments of a hearing that lasted more than three hours.

Daines pressed Becerra repeatedly to come up with a type of abortion restriction that he would support.

“Is there any line you would draw?” the senator prodded, suggesting restrictions on an abortion based on a fetus’s sex or in cases in which developmental disabilities are diagnosed.

The nominee skirted all the examples. Finally, he said: “I will defend the law and support the law that’s in place.”

Republicans challenged Becerra’s suitability, too, on the grounds that he is trained as an attorney, rather than a medical professional. Three of HHS’s approximately dozen confirmed secretaries have had medical degrees in the department’s four decades in its current form.

The Finance Committee will schedule its vote on Becerra after members have two days to send Becerra further questions in writing, and he has a chance to respond.

Correction: An earlier version of this article attributed to Xavier Becerra a remark that people in traditional Medicare tend to be older, less healthy and poorer than those in the private plans. The remark was made by Sen. Sherrod Brown (D-Ohio).