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Washington — Democratic Senator Joe Manchin of West Virginia said Sunday he can no longer support President Biden’s Build Back Better Act, dealing a potentially fatal blow to the $1.75 trillion tax and spending plan that includes Democrats’ key domestic policy initiatives.

“I cannot vote to continue with this piece of legislation. I just can’t. I’ve tried everything humanly possible. I can’t get there,” Manchin told “Fox News Sunday.”

“This is a no on this piece of legislation. I have tried everything I know to do,” he added, citing concerns over inflation, the national debt and the COVID-19 pandemic for his decision.

In a lengthy statement reiterating those concerns, Manchin said Democrats in Washington “are determined to dramatically reshape our society in a way that leaves our country even more vulnerable to the threats we face.”

For months, Manchin has been central to talks over the sweeping legislation, which would rewrite U.S. policy on climate change, health care, paid leave, housing, taxes and other issues. Over the summer, Manchin convinced Mr. Biden and Democratic leaders to scale back their $3.5 trillion initial proposal, setting a $1.75 trillion limit on spending he would be willing to support. But talks broke down over the past week, particularly over the child tax credit, which is set to expire at the end of the year. 

Before announcing his opposition to the bill on Sunday morning, Manchin informed the White House and congressional Democratic leadership of his plans to do so, a person familiar with his actions told CBS News.

While Manchin announced he cannot vote for the legislation, people familiar with his thinking reiterated Sunday that he remains committed to working on those issues through more modest, focused legislation and through regular legislative order. 

“I also think he could find a way to yes on a version of it,” said one of the people. “I don’t see [Build Back Better] as dead dead.”

As written and proposed, the Build Back Better plan would pass through special Senate budgetary rebukes requiring a simple majority vote. Manchin, a moderate Democrat, has pushed for bipartisan cooperation in everything the chamber does since he arrived in the Senate in late 2010. 

In his statement Sunday, Manchin said he will “continue working with my colleagues on both sides of the aisle to address the needs of all Americans and do so in a way that does not risk our nation’s independence, security and way of life.”

Last week, Mr. Biden sounded confident he could craft a deal with Manchin that would satisfy congressional Democrats. “It takes time to finalize these agreements, prepare the legislative changes, and finish all the parliamentary and procedural steps needed to enable a Senate vote,” the president said in a statement last Thursday.

Manchin’s withdrawal of support is a blow to progressive Democrats, who agreed to pass Mr. Biden’s $1 trillion infrastructure plan earlier in the fall with the expectation that Manchin would back the Build Back Better Act.