As Trump Refuses to Concede, G.O.P. Remains Divided: Live Updates

As the Trump campaign continued to pursue long-shot legal challenges and top Republicans remained split on whether to congratulate President-elect Joseph R. Biden Jr. on his projected victory, Democrats took steps on Sunday toward planning for a Biden administration.

Mr. Biden unveiled his official transition website as he prepared to unleash a series of executive actions on his first day in the Oval Office aimed at unwinding Mr. Trump’s domestic agenda and signaling a wholesale shift in the United States’ place in the world.

On the website, buildbackbetter.com, Mr. Biden and Vice President-elect Kamala Harris pledged to be ready on Day 1 to tackle four main priorities for the new, Democratic administration after four years under Mr. Trump: Covid-19, economic recovery, racial equity and climate change.

“A Biden-Harris administration, propelled by the foundation laid by the transition, will lead a just and equitable recovery that rebuilds a strong, inclusive middle class and builds an economy for the future,” they said on the website.

In the first hours after he takes the oath of office on Jan. 20, Mr. Biden has said, he will send a letter to the United Nations indicating that the country will rejoin the global effort to combat climate change, reversing Mr. Trump’s decision to withdraw from the Paris climate accord with more than 174 countries.

He has also vowed that on Day 1 he will move rapidly to confront the coronavirus pandemic by appointing a “national supply chain commander” and establishing a “pandemic testing board,” similar to Franklin D. Roosevelt’s wartime production panel.

He has said he will restore the rights of government workers to unionize. He has promised to order a new fight against homelessness and resettle more refugees who are fleeing war. He has pledged to abandon Mr. Trump’s travel ban on mostly Muslim countries and to begin calling foreign leaders in an attempt to restore trust among the United States’ closest allies.

On the campaign trail, Mr. Biden repeatedly said that he was campaigning as a Democrat but would govern “as an American.” But he and members of his party are eager to systematically erase what they view as destructive policies that the president pursued on the environment, immigration, health care, gay rights, trade, tax cuts, civil rights, abortion, race relations, military spending and more.

Some of that will require cooperation with Congress, which may remain divided next year. But Mr. Biden may be able to achieve some of his goals with nothing more than the stroke of a pen.

He has signaled that his top priority will be demonstrating a much more muscular federal approach to the pandemic than Mr. Trump’s leave-it-to-the-states strategy.

Aides said he would use the power of his office to invoke the Defense Production Act — the Korean War-era law that allows the president to order businesses to manufacture products necessary for national defense — to build up supplies more aggressively than Mr….