The most concrete short-term impact will come from Biden reopening HealthCare.gov insurance markets as coverage has shrunk in the economic turmoil of the coronavirus pandemic. Created under the Obama-era Affordable Care Act, also called “Obamacare,” the marketplaces offer taxpayer-subsidized coverage regardless of a person’s medical history, or preexisting conditions, including COVID-19.

That new three-month “special enrollment period” could begin as soon as Feb. 15, according to a White House summary.

Biden will also immediately reverse a federal policy that bars taxpayer funding for international health care nonprofits offering abortion counseling or referrals. Known as the Mexico City Policy, it can get switched on and off depending on whether Democrats or Republicans control the White House.

Other directives Biden plans to issue Thursday could take months to carry out. Among them, he’ll instruct the Department of Health and Human Services to:

— Consider whether to rescind Trump regulations that bar federally funded family planning clinics from referring women for abortions. The ban on referrals led to Planned Parenthood clinics leaving the program.

— Reexamine a Trump administration policy that allows states to impose work requirements as a condition for low-income people to get Medicaid health insurance. Work requirements have been blocked by federal judges, and the Supreme Court has agreed to hear the issue.

— Review policies that could undermine protections for people with health problems, such as a Trump administration rule that facilitated the sale of short-term health insurance plans that don’t have to cover preexisting medical conditions.

The abortion-related actions will bring Biden immediate praise from women’s rights groups, as well as condemnation from social and religious conservatives. Under President Donald Trump, abortion opponents got free rein to try to rewrite federal policy, and now the political pendulum is swinging back.

Biden also campaigned on repealing longstanding federal prohibitions against taxpayer funding for abortion, but a change of that magnitude to a group of laws known as the Hyde Amendment would require congressional approval.

The regulatory changes Biden is asking federal health officials to undertake aren’t likely to happen overnight because hastily written rules are more easily overturned in court, as the Trump administration found out. Time and again, federal judges ruled that Trump officials ran roughshod over legal requirements for regulators, such as demonstrating they’ve considered all sides of an issue.

The idea of reopening Obamacare’s health insurance markets has broad support, including from consumer groups, professional medical associations, insurers and business organizations.

Although the number of uninsured Americans has grown because of job losses in the coronavirus economy, the Trump administration resisted calls to reopen HealthCare.gov. Failure to repeal and replace Obamacare as he repeatedly vowed to do was one of the former president’s most bitter disappointments. His administration continued trying to find ways to limit the program or unravel it entirely. A Supreme Court decision on Trump’s final legal challenge to the Affordable Care Act is expected this year.

The Obama-era health care law covers more than 23 million people through a mix of subsidized private insurance sold in all states, and expanded Medicaid adopted by 38 states, with Southern states being the major exception. Coverage is available to people who don’t have job-based health insurance, with the Medicaid expansion geared to those with low incomes.

Of some 28 million uninsured Americans before the pandemic, the nonpartisan Kaiser Family Foundation has estimated that more than 16 million were eligible for some form of subsidized coverage through the health law.

Experts agree that number of uninsured people has risen because of layoffs in the coronavirus economy, perhaps by 5 million to 10 million, but authoritative estimates await government studies due later this year.

The special sign-up opportunity is only a down payment on health insurance for Biden, who has promised to build on former President Barack Obama’s health law to push the U.S. toward coverage for all. For that he’d need congressional approval, and opposition to the health law still runs deep among Republicans.