WASHINGTON — President Joe Biden will announce executive action to confront climate change after a key senator blocked legislation, but he’s holding off for now on an emergency decree that would allow him to marshal sweeping powers — and billions of federal dollars — against global warming.

Biden will outline his moves in a speech Wednesday at a shuttered coal-fired power plant in Massachusetts, vowing that he won’t allow a congressional impasse on climate legislation to prevent urgent work to slow rising global temperatures, according to people familiar with the matter.

White House officials are still weighing a separate declaration that climate change is a national emergency — a step that would unlock broad executive powers to propel clean-energy construction, restrict oil drilling and curb fossil fuel use. The emergency order is one of several tactics now under deliberation, as the White House weighs strategies to demonstrate Biden’s commitment to clean energy without jeopardizing ongoing talks on health care legislation in Congress.

Any move to deploy emergency powers against fossil fuels risks alienating Sen. Joe Manchin, the West Virginia Democrat who last week withdrew his support for climate and tax legislation but whose vote is still critical to pass the health measure under fast-track budget reconciliation procedures.

Nevertheless, an emergency order would be a potent way for Biden to show he’s committed to addressing the climate threat before November’s pivotal midterm elections. After Manchin slammed the brakes on clean energy and climate provisions in the reconciliation package last week, discussions accelerated among Biden’s allies and within the White House about steps the president could take unilaterally.

The president has insisted he would “not back down” from the fight. “If the Senate will not move to tackle the climate crisis and strengthen our domestic clean energy industry, I will take strong executive action to meet this moment,” Biden said in a statement Friday in response to reports Manchin had withdrawn his support.

Still, the president does not plan to declare a climate emergency this week, and as of Tuesday morning, White House officials had not made a final decision on measures to be announced in Massachusetts.

In remarks in Somerset, Massachusetts, the president will speak about “tackling the climate crisis and seizing the opportunity of a clean energy future to create jobs and lower costs for families,” the White House said in a statement.

The venue, Brayton Point power station, was a coal-fired power plant that was once the largest in New England and closed in 2017. It’s now primed to serve as a production hub for power cables and other equipment critical for more than a dozen offshore wind farms planned along the East Coast.

The site embodies the U.S. transition from fossil fuels to renewable energy as well as the president’s bid to deploy 30 gigawatts of offshore wind power by 2030. Biden has repeatedly portrayed the movement toward renewable and cleaner energy sources as a jobs engine for the U.S. economy.

While the White House hasn’t settled on declaring a climate emergency, the move is tempting because of the authorities it would unlock for the president and his administration. Under an emergency declaration, he could redirect federal funding to clean-energy construction, steer aid to communities on the front lines of climate change and even curb the export of fossil fuels driving global warming.

Former President Donald Trump used a similar tactic to divert billions of dollars to begin construction of a wall on the US southern border after Congress refused to appropriate the funding. Trump’s move was criticized by Democrats at the time as an illegal end-run around Congress and faced multiple court challenges.

Biden revoked Trump’s emergency declaration shortly after assuming office, before it had been fully litigated.

It would be no less controversial if Biden seized powers typically deployed against unexpected national disasters to address an ongoing climate crisis. Some good-government advocates have warned against the move, cautioning that enduring climate action requires special tools from Congress, including tax credits to spur renewable power projects and advanced energy manufacturing included in the now-stalled climate bill.

But many Democrats, ready to move on from that approach after more than a year of negotiations, are pushing Biden to act aggressively now.

“The potential to enact the legislation is dead,” said Sen. Jeff Merkley, an Oregon Democrat. The development “frees up the president to use the full powers of the executive branch — and those full powers certainly include a climate emergency.”

Sen. Ed Markey, a Massachusetts Democrat and author of the Green New Deal, has lobbied the White House to seize emergency authority.

“I’m confident that the president is ultimately ready to do whatever it takes in order to deal with this crisis,” Markey told reporters Tuesday. “He’s made that clear in his statement last Friday, and I think coming to Massachusetts is a further rearticulation of that.”

By declaring a national emergency, Biden could tap more than 100 special powers normally intended to address hurricanes, terrorist attacks and other unforeseen events.

For instance, under the Stafford Disaster Relief and Emergency Assistance Act, the president could direct the Federal Emergency Management Agency to construct renewable energy projects using federal money. He could also trigger a national security exemption in a 2015 law that lifted a decades-long ban on most crude exports, re-imposing licensing requirements and other restrictions to curtail overseas oil sales.

Even without declaring an emergency, Biden can use the federal government’s purchasing power to compel clean-energy acquisitions. He’s already invoked Cold War-era authorities under the Defense Production Act to propel US manufacturing of an array of critical energy technologies, including solar panels, fuel cells and heat pumps.

Some analysts believe Biden might wield emergency powers in a more targeted way, such as by seeking to increase clean energy production.

“Courts have generally given presidents wide latitude on emergency declarations,” Benjamin Salisbury, director of research at Height Capital Markets, said in a note for clients on Tuesday. But major steps to limit fossil fuel production, transportation and consumption “could be vulnerable to legal challenge,” he said.