President Donald J. Trump listens to Judge Brett M. Kavanaugh during a July 9 announcement of his nomination to the Supreme Court. (Jabin Botsford/The Washington Post)

Senate Democrats and their allies are casting Judge Brett M. Kavanaugh as a grave danger to Americans’ ability to afford health care as a central theme of their high-decibel campaign to block his ascension to the Supreme Court.

But after a half-dozen years in which the high court has repeatedly upheld the essence of the Affordable Care Act, Kavanaugh, if confirmed, would be less likely to help decide cases threatening the law’s survival than a mosaic of narrower issues, often arising from the Trump administration’s eagerness to chip away at parts of the law.

According to health-law specialists across the ideological spectrum, cases most likely to come before the court’s next set of nine justices can be expected to affect the quality of insurance benefits, poor Americans’ access to Medicaid and who can provide contraceptives to low-income women.

“The most important cases, as least in the near term, that Justice Kavanaugh would rule on would be not broadside constitutional challenges to the Affordable Care Act, but Trump administration actions to pare back and, in some cases, sabotage the ACA,” said Nicholas Bagley, a University of Michigan law professor who supports the law.

From his dozen years on the U.S. Court of Appeals for the District of Columbia Circuit, the most telling clues as to how Kavanaugh would regard such issues, specialists say, appear in opinions and other writings unrelated to health care, such as his broad view of presidential powers and a rigorous standard for the limits of federal agencies’ proper reach.

“It’s his deeply held view about the role and power of agencies that has the potential to play itself out in a series of health-care cases,” said Sara Rosenbaum, a professor of health law and policy at George Washington University. “Now, he [would be] confronted with many potential overreach cases involving this administration.”

Crucial as they are to the United States’ health-care system and its patients, these issues do not amount to the full destruction of the ACA that Democrats say would inevitably result if the Senate confirms Kavanaugh, President Trump’s second nominee for the Supreme Court.

“We have a clarion call . . . for the American people,” Senate Minority Leader Charles E. Schumer (D-N.Y.) said Wednesday at a news conference with a quartet of Democratic colleagues. “Rise up before so many of you will no longer be able to get insurance because someone in your family is sick.”

The Democrats are focused on the piece of the ACA that prevents insurers from charging more or refusing to sell health plans to people with preexisting medical conditions — a facet that polls consistently show is popular with the public.

Sen. Chris Van Hollen (D-Md.), said that after Congress’s Republican majority failed last year to dismantle much of the ACA, Trump wants “to go to the courts . . . They have found their man.”

The Democratic senators also point to a federal lawsuit, filed in Texas by the attorneys general of 20 Republican-led states, alleging that the ACA has become unconstitutional because Congress is removing the tax penalties for those who flout the law’s requirement that most Americans carry health coverage. The Justice Department recently told the court it would not defend the law in the case.

Senate Republicans hold a slender 51-49 majority. So far, it remains unclear whether this attempt to frame the nomination as a fight for the future of health care might influence two Republican moderates, Sens. Susan Collins (Maine) and Lisa Murkowski (Alaska), who could prove pivotal to Kavanaugh’s fate because they support the preservation of abortion rights. Both voted against an unsuccessful GOP bill to repeal much of the ACA last year. On Monday night, shortly after the president’s prime-time announcement of his selection, Collins said Kavanaugh has “impressive credentials.” Murkowski this week has merely said, “we’ve got some due diligence we’ve got to do.”

Nor is it clear whether Democrats’ portrayal of Kavanaugh will prevent the defection of a few in their caucus facing difficult reelection campaigns in red states. One of them, Sen. Claire McCaskill (D-Mo.), brushed off a question about Kavanaugh on Wednesday, saying that she has not yet vetted him.

Academics with expertise in health-care law do not rule out the possibility that, with a district court judge who has previously been hostile to the ACA and a conservative appellate court, the Texas case could go up to the Supreme Court. But even health-law experts who oppose the law are not predicting it.

Jonathan Adler, a Case Western University law professor and an architect of the ACA challenge that the Supreme Court rejected in 2015, said the Texas lawsuit “may be the last of the attempted death blows.” Saying the suit’s arguments are weak, Adler predicted: “I can’t imagine the Supreme Court takes it.”

Even if that case reached the high court, Bagley said it is unclear based on Kavanaugh’s writings which way he would vote. The lawsuit’s central argument is that Congress’s decision late last year to eliminate the penalty for being uninsured cannot be separated from the rest of the law. Bagley noted that Kavanaugh wrote recently in the Harvard Law Review that courts might sever a provision of a law “to the narrowest extent possible . . . This . . . has the benefit of stopping judges from trying to guess what Congress would have wanted, an inherently suspect exercise.”

Abbe Gluck, a Yale law professor, said “a bigger question [is] about how much the court is going to allow this chipping away” at elements of the ACA through executive actions. “Trump has said, ‘My goal is to force the law to collapse under its own weight.’ . . . Judge Kavanaugh is a proponent of presidential power. But we don’t know how anyone will rule on that. That is a new legal question.”

Last last month, a D.C. federal judge ruled against the administration in a lawsuit challenging the Department of Health and Human Services’ decision to let Kentucky become the first state to require many poor residents to work or perform other “community engagement” to qualify for Medicaid. The administration has not said whether health officials plan to reconsider Kentucky’s application, as U.S. District Judge James Boasberg directed, or appeal the ruling.

Health-law experts also predict that lawsuits will challenge the administration’s efforts to foster health plans that are relatively inexpensive because they bypass ACA benefits requirements and some consumer protections. The Labor Department recently issued a rule expanding “association health plans,” for the first time allowing self-employed people to buy such policies, originally intended for small business to band together under limited circumstances to negotiate better insurance rates. HHS is finishing a rule to increase Americans’ ability to rely on short-term health plans originally meant as a brief bridge for people between jobs; such plans do not need to meet the ACA’s preexisting conditions protections.

Already, the Supreme Court is being asked to take a pair of cases involving states’ decisions to bar Planned Parenthood clinics from receiving public money to provide contraception and other services to people on Medicaid. Calling them “blockbuster cases,” Rosenbaum said they raise legal questions about both consumers’ ability to choose their own providers of care and whether people on Medicaid are allowed to sue over the way the program is run.

“What you have is a cluster of cases that heavily focus on the question of agency overreach,” GWU’s Rosenbaum said. “This is right up maybe-justice Kavanaugh’s alley.”

Sean Sullivan contributed to this report.