Donald Trump’s surprise election Tuesday as U.S. president means the repudiation of Barack Obama’s legacy and a strong likelihood Republicans will undo many of his accomplishments, including Obamacare and trade deals, as well as seek tax cuts for the rich.

While Trump has made broad promises, he has offered few details of how he would execute them. Even though Republicans hold control of both chambers of Congress, it’s unclear whether Trump will have devoted partners. Most lawmakers from the party—including House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell—haven’t embraced his highest-profile ideas, such as building a wall on the Mexican border.

It’s also not clear who will populate his cabinet. He has a small cadre of close advisers, while many prominent Republicans have said they don’t intend to serve with him.

Here’s a look at Trump’s top priorities:

Immigration

Trump surged to the Republican nomination in part based on a hard-line immigration policy that he framed as a rejection of Obama’s more welcoming posture.

Trump said his first day in office would be devoted in large part to beginning an overhaul of the U.S. immigration system, setting aside funding to triple the number of immigration control agents and deporting more than two million people with criminal records. He’s declined to say whether his administration would pursue deportations of the millions of undocumented immigrants in the U.S. who haven’t committed crimes.

He has also said the Mexican government would pay at least part of the expenses for construction of a border wall. The Mexican government has said it will pay nothing.

Legal immigration from several countries will be completely banned for an indefinite period in the interest of national security, Trump has said. He once pledged to ban all Muslims from entering the U.S. but has since modified his position and now says he would impose “extreme vetting” to keep out terrorists. Entire countries that have been “compromised” by terrorism would be blacklisted from sending immigrants to the U.S. under Trump’s policy. It’s not clear how he would implement such a ban or whether it’s constitutional.

Other than saying the U.S. would stop accepting refugees from Syria, Trump’s campaign hasn’t specified which countries would be on the list.

Trade

Trump has pledged to end decades of American orthodoxy on trade policy, charging that past deals have decimated the U.S. manufacturing sector.

He says he’ll take a hard line against U.S. trading partners, including top allies, by seeking to renegotiate or nullify existing trade deals, and he plans to take a protectionist approach with China, which he has accused of manipulating its currency to undercut U.S. industry. He’s said he would label China a currency manipulator, bring trade cases against it at the World Trade Organization and potentially slap new tariffs on the country’s goods.

One of Trump’s top targets: The North America Free Trade Agreement, or NAFTA, a deal between the U.S., Mexico and Canada, signed by President Bill Clinton in 1993. Trump has said the agreement is the worst trade deal in U.S. history and that his administration would immediately call on Mexico and Canada to renegotiate.

He’s also promised to abandon the Trans-Pacific Partnership trade deal between the U.S. and 11 Pacific Rim nations. Congress has yet to ratify the pact, which was supported by President Barack Obama and opposed by both Trump and Democratic candidate Hillary Clinton.

Taxes

Trump’s tax plan largely adheres to Republican doctrine, offering a historic across-the-board cut in rates. He would reduce the number of federal tax brackets to three from seven, with a top rate of 33 percent for married couples earning $225,000 or more. The current top rate is 39.6 percent.

He’s called for reducing the U.S. corporate tax rate to 15 percent, down from 35 percent, in an effort to keep companies from leaving for countries with lower rates. Trump supports a one-time repatriation of U.S. companies’ corporate profits held overseas, taxed at 10 percent.

His plan includes ending the carried-interest provision of the tax code, which eases the tax burden for hedge-fund managers. Trump would also repeal the estate tax and offer new tax deductions for childcare expenses.

The conservative Tax Foundation found that Trump’s tax plan may reduce federal revenue by at least $2.6 trillion over 10 years, after accounting for economic growth that his proposals might stimulate.

The center-left Tax Policy Center found that the 10-year reduction in revenues would be $6.2 trillion and that the top 1 percent of taxpayers would receive almost half the benefits.

Health Care

Trump says he’ll ask Congress to immediately repeal the Affordable Care Act, Obama’s signature domestic achievement. He has criticized the law for large premium increases in its government-run insurance markets.

Even if Democrats in the Senate are able to block wholesale repeal, Republicans could gut some of the law’s key provisions, such as premium subsidies for insurance, a requirement that Americans carry insurance and an expansion of Medicaid for the poor.

Some of the law’s popular consumer protections would likely remain in place, including the requirement that insurers cover everyone regardless of their health and the prohibition against charging sick people higher premiums. It’s not clear how or if his administration would help insurers struggling to cope with those rules.

His replacement plan for Obamacare, he has said, would include more widespread use of health savings accounts, which allow people to sock away money in retirement-style accounts to spend when they need care, along with a “national market” for health insurance.

Insurers in any state would be allowed to sell plans in all others, ending the current system of state-level regulation. State insurance regulators, including Republicans, have criticized that idea, a longstanding Republican proposal, because they say consumer protections would be weakened and out-of-state insurers would have trouble assembling sufficient networks of doctors and hospitals.

About 20 million people who didn’t previously have health insurance gained coverage under Obamacare. Trump has offered no estimate of how many of them would be insured under his approach