Sen. Joe Manchin (D-W.Va.) announced Wednesday he planned to support a deficit reduction package that addressed both climate change and prescription drug reform, a stark reversal for the one senator who has been blocking key planks of President Biden's agenda.

Why it matters: The declaration from Manchin marks yet another about-face in a year-long negotiation over the size and scope of a Democrat-only reconciliation package.

By the numbers: The nascent deal would generate $313 billion in new revenue over 10 years by increasing the corporate minimum tax to 15%, according to a one-page summary distributed by Manchin's office.

• It would bring in an additional $124 billion from enhanced Internal Revenue Service enforcement.
• And in a major blow to the private equity industry, the agreement calls for another $14 billion by treating so-called "carried interest" as regular income and taxing it at a higher rate.

For the climate provisions, the proposed package would spend $369 billion, while providing another $64 billion to shore up the Affordable Care Act for three years.

• That would leave an additional $300 billion for deficit reduction.

Driving the news: The reversal came just hours after the Senate passed a $280 billion package to support U.S. domestic semiconductor manufacturing.

• Senate Minority Leader Mitch McConnell (R-Ky.) had previously threatened to hold the CHIPS Act hostage if Democrats continued negotiating with Manchin, but that threat evaporated after Manchin opposed new climate spending earlier this month.

What he's saying: "I now propose and will vote for the Inflation Reduction Act of 2022," Manchin said in a statement.

• "Rather than risking more inflation with trillions in new spending, this bill will cut the inflation taxes Americans are paying, lower the cost of health insurance and prescription drugs, and ensure our country invests in the energy security and climate change solutions we need to remain a global superpower through innovation rather than elimination."

President Biden said in a statement that he had spoken to Manchin and Senate Majority Leader Chuck Schumer (D-N.Y.) Wednesday afternoon and expressed support for the deal, calling it "the action the American people have been waiting for."

The other side: Republicans appeared to be livid as the news broke, with some accusing Manchin of being "deceitful" about his true intentions on reconciliation in order to release McConnell's hold on the chips bill.

• Some Republicans called for every member of their caucus to vote against the CHIPS Act in the House, potentially endangering another top priority for Biden that until Wednesday evening appeared to be heading for his desk.
• "Democrats have already crushed American families with historic inflation.   Now they want to pile on giant tax hikes that will hammer workers and kill many thousands of American jobs," McConnell tweeted.

The big picture: Two weeks ago, in response to the 9.1% Consumer Price Index release, Manchin said that he was only willing to support a bill that allowed Medicare to directly negotiate prescription drug prices.

• That pronouncement effectively killed any prospects for the $300 billion in spending to address climate change that Manchin previously supported. Democrats were depressed and vented their anger at Manchin.
• But privately, some Senate Democrats continued to negotiate.

This story has been updated with new details on the proposed package.