The United States should be allocating a lot more than $3.5 trillion to address fundamental economic, social, and environmental challenges that existed before the coronavirus pandemic hit, and that have only become more consequential over the course of the harrowing last year.

“That $3.5 trillion [figure] is already the result of a major, major compromise, and at the very least this bill should contain $3.5 trillion,” Senate Budget Committee chair Bernie Sanders, the Vermont independent who caucuses with the Democrats, says of the reconciliation measure he is trying to secure with 50 Democratic votes and a tie-breaking boost from Vice President Kamala Harris.

Unfortunately, not every Democrat agrees with Sanders, or the many Senate Democrats who the Vermont senator says share his view that a $6 trillion commitment would have been better policy and better politics.

West Virginia Senator Joe Manchin, the Democrat who makes it his mission to throw wrenches into the Democratic machine, says he can’t accept the $3.5 trillion figure. Echoing the line of business lobbyists who object in particular to the taxes on multinational corporations and billionaires that would fund the plan, Manchin is suggesting that he wants to see a dramatic cut in the figure that was agreed upon over the summer by Sanders, Senate majority leader Chuck Schumer (D-N.Y.), and President Joe Biden.

Manchin talks about taking the number down to $1.5 trillion, perhaps even as low as $1 trillion.

Such a shift would ease the burden on the corporate interests that have so generously supported Manchin’s political career—over the past five years alone he’s taken in more than $1 million from donors aligned with the securities and investment industry, according to Open Secrets. At the same time, it would severely undermine the ambitious agenda of the budget plan, which includes proposals to expand Medicare to cover vision, hearing, and dental needs, guarantee family and medical leave, extend the child tax credit, make community-college education free, extend the child tax credit, and fund initiatives to create jobs and fight climate change.

All of those proposals are necessary, says Natalia Salgado, the director of federal affairs for the Working Families Party. “We can’t afford to lose a single cent in this $3.5 trillion,” she says. “Every single penny will count.”

The Rev. William Barber II is blunter. “Stop being a political coward!” he thundered after Manchin suggested Democrats should pause in the quest to “go big” on social safety net issues. “If you’re scared of the donors, say it, but don’t say we have done enough and made the playing field more level.”

The cochair of the Poor Peoples Campaign has labeled Manchin’s attempt to downsize Democratic ambitions “sinful, immoral, and a form of political malpractice.”

That’s a message that President Biden, the man who ultimately will have to sort out Democratic differences over the budget plan, needs to recognize and make his own.

The core components of the budget plan poll exceptionally well. A solid majority of all Americans, and over 90 percent of all Democrats, expressed support for the $3.5 trillion proposal, according to a late August USA Today/Suffolk University survey. That should matter to even the most cautious Democrats, as their party must maintain voter enthusiasm going into the difficult 2022 election cycle.

“Failure to pass a bill, with so many popular items, would be shooting ourselves in the foot for the 2022 elections,” says Progressive Change Campaign Committee cofounder Adam Green, who has been arguing against any trimming of the $3.5 trillion plan. “It’s just malpractice to not pass this bill.” Congressional Progressive Caucus chair Pramila Jayapal (D-Wash.) warns, “If we don’t deliver, then I think all of the people who came out and voted for Democrats to take control of the House, the Senate, and the White House [in 2020] are going [to say in 2022], ‘that’s it.’”

This is one of those moments where doing what is morally necessary is also politically necessary. To get that logic across, however, activists are going to need to upend the media narrative that imagines this as nothing more than a political rumble between Manchin and Sanders—or, worse yet, a debate about how low Democrats can go. As Sanders explains, “If the discussion is about personalities and negotiations, people get frustrated with Washington. But if the discussion is about what’s in the plan, about how it meets the needs of working families, people get excited.”

That excitement could yet tip the balance in favor of the $3.5 trillion plan. But for that to happen, this can’t just be an inside-the-Beltway debate. Members of the Senate need to hear from the grass roots. To that end, 94 labor, environmental, faith, justice, and community-focused organizations—including the AFL-CIO, Public Citizen, People’s Action, the Sunrise Movement, the Economic Policy Institute, and the Institute for Policy Studies—have issued a call to action urging Congress “to stand up to pressure from lobby groups representing the wealthy and big corporations and pass President Joe Biden’s $3.5 trillion Build Back Better plan.”

Explaining, “This down payment on the needs of our communities begins to meet the full scale of our country’s climate, poverty, and inequality emergencies and reform a tax system rigged in favor of the wealthy and large corporations,” the groups say:

The passage of this plan would be an important move toward addressing the interlocking crises of poverty, inequality, climate change, and racism. Ultimately, our nation needs a 3rd Reconstruction to provide living wages, strengthen our democracy, curb violence and militarism in our communities, and prioritize the millions of poor and low-income people in the country and their needs. To advance toward that goal, Congress must step up and do the right thing and live up to its Constitutional and moral commitments to establish justice and the general welfare. Now is not the time to let deep-pocketed corporate lobbyists stand in the way of vital public investments in an economy that works for all of us.

While Manchin and his “centrist” compatriots parrot Republican fretting about debt and deficits, the groups push back, arguing, “Lawmakers’ desire to fully pay for these investments should not affect the size or scope of the package. Congress can easily raise more than $3.5 trillion in revenue from corporations and the wealthy who have seen their profits and net worth skyrocket for decades. The wealth of the country’s 708 billionaires alone rose by $1.8 trillion, or 62 percent, during the pandemic—enough to pay for half of the ten-year cost of the $3.5 trillion package.”

That’s a powerful message. If Joe Biden is sincere about wanting be as bold as former Democratic presidents such as Franklin Delano Roosevelt and Lyndon Johnson, he should embrace it, amplify it, and take it on the road—to West Virginia and every other state where a Democratic senator is deferring to lobbyists rather than delivering for the American people.