Now, confronted with a moment that many believe will upend the 2020 election — the death of Justice Ruth Bader Ginsburg and the prospect of a bitter Supreme Court confirmation battle — Mr. Biden’s campaign is sticking to what it believes is a winning strategy. Campaign aides said Saturday they would seek to link the court vacancy to the health emergency gripping the country and the future of health care in America.

While confirmation fights have long centered on hot-button cultural divides such as guns and especially abortion, the Biden campaign, at least at the start, plans to chiefly focus on protecting the Affordable Care Act and its popular guarantee of coverage for people with pre-existing conditions.

Arguments in a seminal case that could determine the future of the health care law are set for a week after Election Day, with the administration supporting a Republican effort to overturn it. Mr. Biden will accuse the president, as he already has, of trying to eliminate protections for pre-existing conditions during a pandemic, aides said, with the stakes heightened by a Supreme Court now short one of the liberal justices who had previously voted to keep the law in place.