Sen. Bernie Sanders, I-Vt., offered harsh criticism for Sen. Joe Manchin Sunday after the Democrat from West Virginia indicated he would vote against President Biden’s roughly $2 trillion social spending packaged known as the Build Back Better Act. 

"If Mr. Manchin doesn’t want to support us, look we’ve been dealing with Mr. Manchin month after month after month," Sanders told CNN’s Jake Tapper on "State of the Union" Sunday. "But 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."

MANCHIN SAYS HE ‘CANNOT VOTE’ FOR BUILD BACK BETTER: ‘I’VE DONE EVERYTHING HUMANLY POSSIBLE' 

Sanders argued that Manchin’s "no" vote meant the West Virginian does not have the guts to stand up to special interest groups to lower the cost of prescription drugs and is failing to expand home healthcare and Medicare. What is going on now in Washington, according to Sanders is that interest groups are "pouring hundreds and hundreds of millions of dollars to make sure we continue to pay the highest prices in the world for prescription drugs and the rich do not start paying their fair share of taxes."

Sen. Bernie Sanders arrives before President Joe Biden addresses a joint session of Congress in the House chamber of the U.S. Capitol April 28, 2021. (Melina Mara-Pool/Getty Images)

"I would have hoped that we could have had at least 50 Democrats on board," he said.

"The American people have got to understand what is at stake," Sanders continued. "For decades now, what Congress has been doing, giving tax breaks to the rich, not standing up to the drug companies, so we end up paying the highest prices in the world for prescription drugs, ignoring climate change, the President of the United States and almost every Democrat is trying finally to address these issues." 

Machin’s vote against the massive spending bill – which aimed to overhaul the social safety net, healthcare system, and climate and tax policies – severely jeopardizes Democrats’ plan to push forward the legislation through reconciliation, which requires 50 votes to pass. 

Sanders said Sunday he would still want the bill to go to a floor vote. 

"West Virginia is one of the poorest states in this country," Sanders said. "I’ve been to West Virginia a number of times and it’s a great state with beautiful people, but it’s a state that’s struggling. 

"He’s going to have to explain to the people of West Virginia why he’s rejecting what the scientists of the world are telling us," Sanders continued about Manchin, "that we have to act boldly and transform our energy system to protect future generations from the devastation of climate change." 

Speaking with "Fox News Sunday," Manchin said he has spoken with Biden, House Speaker Nancy Pelosi, D-Calif., and Senate Majority Leader Chuck Schumer, D-N.Y., but could not reach an agreement. Between ongoing inflation, the national debt, "geopolitical unrest," and the COVID-19 pandemic, he said the legislation being pushed by his fellow Democrats was too much.

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Manchin had previously proposed a $1.7 trillion price tag for the spending package, but he said his Democratic colleagues did not make the necessary compromises. 

The West Virginia senator said that instead of trying to pass such a large spending bill, Congress should be more focused on tackling the omicron variant of COVID-19 that has led to rising case numbers. He also said the government should be addressing inflation that has "harmed a lot of Americans." 

Fox News' Ronn Blitzer contributed to this report.