WASHINGTON - House Democrats on Friday are expected to approve a sweeping package to lower health-care costs, combat climate change, raise taxes on some large companies and reduce the deficit, sending the once-imperiled proposal to President Joe Biden's desk.

With debate set to begin in the morning, and a vote on passage likely later in the afternoon, the chamber is on track to deliver for Democrats a major legislative victory - one that party lawmakers already have touted on the campaign trail in a bid to protect and expand their majorities in this year's midterm elections.

"This is a fabulous bill we're going to pass," House Speaker Nancy Pelosi, D-Calif., told The Washington Post in an interview Thursday before the vote. "It's not anything that anybody, three months ago, would have said is a possibility. But it is, and we'll have a good strong vote, send it to the president . . . and the clock will start ticking."

The bill, known as the Inflation Reduction Act, includes the largest-ever single investment in combating climate change. Democrats say the roughly $370 billion burst in spending will allow the United States to lower emissions 40% below 2005 levels by the end of the decade. The proposal also includes new programs to cap and lower seniors' drug costs while sparing about 13 million low- and middle-income Americans from increases in their insurance premiums that otherwise would take effect next year.

"We've been fighting for decades - for decades - for the ability for the [government] to negotiate for lower prices," Pelosi said, referring to the efforts to make seniors' medicines more affordable.

"We cannot undervalue what this legislation does [over] what it does not do, and families will be very affected. The kitchen table issues are about the cost of health care."

Democrats hope to fund the package through changes to tax laws, including a new minimum tax on some billion-dollar corporations that currently pay nothing to the federal government. They also seek taxes on companies that buy back their own stock, and money to help the Internal Revenue Service pursue tax cheats. Party lawmakers say the measures are enough to cover the costs of their bill and reduce the deficit by about $300 billion, though they have yet to furnish a final fiscal analysis.

Democrats need only band together in the House to overcome fierce and likely unanimous Republican opposition, having prevailed in a successful, party-line Senate vote on Sunday. The bill itself was forged in that chamber, after Majority Leader Chuck Schumer, D-N.Y., brokered a long-elusive deal with Sen. Joe Manchin, D-W.Va., last month.

Rep. Rosa DeLauro, D-Conn., the leader of the House Appropriations Committee, described the economic package ahead of the House vote as "historic legislation that really deals with issues that haven't been dealt with for years."

But House Republicans have sought to mount a stiff, united front against it anyway. They have attacked it as a tax increase on families, even though the bill does not raise individuals' rates. And they have said it will worsen inflation while resulting in intrusive IRS audits, even though some of the money is focused on improving the agency's well-known deficiencies.

Some Republicans have suggested they could weaponize the House's procedural rules to slow the debate on Friday. GOP lawmakers did that in November, when Democrats considered their larger package known as the Build Back Better Act. While the House ultimately adopted the bill, the vote came after Minority Leader Kevin McCarthy, R-Calif., seized on the speaking privileges afforded to party leaders - and held up the chamber floor for more than eight hours.

"Right now, we're trying to defeat the bill," said Rep. Steve Scalise, R-La., the House minority whip, in an interview before debate began. "If they vote for it, they know good and well it's going to hurt low- and middle-income families."

Reacting to the GOP opposition, Pelosi said the looming vote would offer Democrats a "big contrast" with their political foes entering this year's midterm elections. She later added: "This is the path we're on. The Republicans want to take us off this path."

The House vote Friday marks the culmination of a long and winding debate that began last spring with the release of Biden's blueprint, dubbed the "American Families Plan," which marked the start of a broader Democratic effort to rewire the economy in the wake of the pandemic. The party's proposal eventually would become known as the Build Back Better Act, borrowing from the president's 2020 campaign slogan.

House Democrats adopted the roughly $2 trillion measure in November, despite months of warfare between the party's own members. Liberals had sought a vast piece of spending legislation that greatly grew the role of government in Americans' lives, while moderates urged more fiscal restraint. The tension at one point prompted Biden himself to intervene in October with a rare appearance on Capitol Hill, during which he urged unity around his economic agenda.

Yet their bill would never even see a vote in the Senate, where Manchin said last winter that he could not support spending so much given economic and geopolitical uncertainty. The moderate West Virginian's opposition infuriated liberal lawmakers, who felt the party's agenda - and in many ways its political prospects - had been hijacked by a single member who did not reflect the party's broader views.

Even in its more scaled-back, renamed form, Democrats this week have hailed the Inflation Reduction Act as urgently needed and immediately beneficial to families in financial need. Pelosi said in the interview Thursday that she had emphasized to members that they should "respect the bill for what it does" rather than "make judgments about it for what it does not."

The House speaker said the bill belonged to a longer line of recent legislative accomplishments, including the passage of a $1.9 trillion coronavirus relief package last year, the $1.2 trillion bipartisan infrastructure law approved months later, and action to deliver new restrictions on guns approved after the school shooting in Uvalde, Texas, in May.

"There's been a stranglehold of the gun industry, the pharmaceutical industry and the fossil fuel industry on Congress," Pelosi said. "And right now, we have changed that dynamic. The leverage is now with the people's interest, not the special interest."