WASHINGTON, Dec 19 (Reuters) - U.S. Senator Joe Manchin, a moderate Democrat who is key to President Joe Biden"s hopes of passing a $1.75 trillion domestic investment bill, said on Sunday he would not support the package, drawing a sharp rebuke from the White House. Manchin appeared to deal a fatal blow to Biden"s signature domestic policy bill, which is known as Build Back Better and aims to expand the social safety net and tackle climate change. "I cannot vote to continue with this piece of legislation," Manchin said during an interview with the "Fox News Sunday" program, citing concerns about inflation. "I just can"t. I have tried everything humanly possible." He then released a statement accusing his party of pushing for an increase in the debt load that would "drastically hinder" the United States" ability to respond to the coronavirus pandemic and geopolitical threats. "My Democratic colleagues in Washington are determined to dramatically reshape our society in a way that leaves our country even more vulnerable to the threats we face," Manchin said in a statement. The White House responded angrily, accusing him of breaking his promise to find common ground and get the bill passed. White House press secretary Jen Psaki said Manchin"s comments "represent a sudden and inexplicable reversal in his position." Biden"s administration would find a way to move forward with the legislation in 2022, she said. Many Democrats feel passage of the bill is essential to the party"s chances of maintaining control of Congress in next year"s elections. The White House had hoped to keep negotiations cordial and private to avoid alienating Manchin, who represents West Virginia, a state that Biden lost to former President Donald Trump by almost 40 percentage points in the 2020 election. But many top Biden allies believe Manchin is damaging the Democratic president"s political future, and Psaki"s public rebuke of the senator suggested a new phase in Biden"s push for legislation he regards as essential to his legacy. Manchin"s comments also drew outrage from liberal Democrats. "Let"s be clear: Manchin’s excuse is bullshit," U.S. Representative Ilhan Omar, a Democrat from Minnesota, said on Twitter. U.S. Senator Joe Manchin (D-WV) arrives at the U.S. Capitol in Washington, U.S., September 27, 2021. REUTERS/Elizabeth Frantz U.S. Senator Joe Manchin (D-WV) arrives at the U.S. Capitol in Washington, U.S., September 27, 2021. REUTERS/Elizabeth Frantz Senator Bernie Sanders, who helped shape the bill, called for a vote to be held on the package of measures anyway. The bill would raise taxes on the wealthy and corporations to pay for a host of programs to thwart climate change, boost healthcare subsidies and provide free childcare. Biden has argued that lowering such costs is critical at a time of rising inflation and as the economy recovers from the fallout of the coronavirus pandemic. Republicans say the proposed legislation would increase the federal deficit, fuel inflation and hurt the economy. UPHILL STRUGGLE Manchin"s support is crucial in a chamber where the Democrats have the slimmest margin of control and Republicans are united in their opposition to the bill. Even if Manchin were somehow convinced to back the bill, the White House would still have to win over Senator Kyrsten Sinema, another moderate Democrat who has not committed to supporting it. Though talks with Manchin had been going poorly, Biden"s aides had expressed confidence in recent days that they would eventually secure a deal. Sanders, a democratic socialist who is aligned with Democrats in the Senate, told CNN on Sunday that he thinks there should still be a vote on the proposed legislation, despite Manchin"s opposition. "If he doesn"t have the courage to do the right thing for the working families of West Virginia and America, let him vote no in front of the whole world," Sanders told CNN. Biden last month signed into law a $1 trillion infrastructure bill designed to create jobs by dispersing money to state and local governments to fix crumbling bridges and roads and by expanding broadband internet access. Liberal Democrats in Congress had pushed for the coupling of the Build Back Better legislation with the infrastructure bill in the hope of ensuring the passage of the former. U.S. House of Representatives Speaker Nancy Pelosi, a Democrat, led an effort in September to decouple the two bills. "This is exactly what we warned would happen if we separated Build Back Better from infrastructure," Omar said on Twitter.