Tensions are rising among congressional Democrats as the party’s $3.5 trillion spending plan draws ever closer to a stalemate.

Democrats’ frustrations, which have been simmering for weeks, are boiling over as lawmakers return to Washington and immediately dive into a debate over tax hikes to pay for the plan. On Monday, the House Ways and Means Committee released its tax proposals.

Democrats are racing against the clock to finish drafting the $3.5 trillion spending bill by Wednesday and have it on the House floor by the end of the month, two deadlines that have sparked criticism from moderates. Manchin and other centrists are also likely to be concerned about a number of tax provisions, which may not go far enough in the eyes of House and Senate liberals.

Veteran Democrats say the fights are to be expected, but that the differences are real and difficult to overcome.

The fights are becoming more public, with various members sparring in television interviews and on social media.

Manchin used a pair of television interviews to reiterate his opposition to $3.5 trillion in spending and to respond to criticism from Rep. Alexandria Ocasio-Cortez (D-NY), whom he referred to as a “young lady” whom he had only met briefly. The remarks sparked immediate progressive backlash, with Senate Budget Committee Chairman Bernie Sanders (I-Vt.) declaring that Manchin’s demand for a much lower price than $3.5 trillion is “unacceptable.”

“In Washington, I usually know my questions of power are getting somewhere when the powerful stop referring to me as ‘Congresswoman’ and start referring to me as ‘young lady’ instead,” Ocasio-Cortez tweeted.

The spat between Manchin and the two progressives is, in many ways, a proxy battle for the larger schisms that are forming among moderates and progressives over the party’s two-pronged infrastructure strategy. Moderates want the Senate-passed $1 trillion infrastructure bill to reach President Biden’s desk as soon as possible, while progressives want to use the larger bill to fulfill a number of promises, such as combating climate change, expanding Medicare, and immigration reform, before taking final action on the narrower bill.

With little room for error, Biden and Democratic leaders must overcome their differences. Speaker Nancy Pelosi (D-Calif.) can lose only three of her members, whereas Majority Leader Charles Schumer (D-N.Y.) can lose none in a 50-50 Senate.

Progressives have taken a hard stance in favor of keeping the spending bill at $3.5 trillion. Last month, Democrats in both the House and Senate passed a budget resolution that allowed them to pass a bill worth up to $3.5 trillion without the support of Republicans.

However, moderates in both chambers have expressed concern about the spending, with Manchin and Sen. Kyrsten Sinema (D-Ariz.) specifically stating that they cannot support $3.5 trillion.

Even as major components of the Democratic plan, such as how to pay for it, remain in flux, Democratic-led House committees are voting on portions of the bill.

Senator Elizabeth Warren (D-Mass.) praised the House’s child care language but added, “I’d like to see us do more to make billionaires, giant corporations, and tax cheats pick up the ticket for this package.”

Durbin noted that some progress has been made, with four to five Senate committees working out agreements with their House counterparts ahead of the deadline on Wednesday. Nonetheless, a dozen people are involved in the bill’s drafting, implying that more frantic work will be done on both sides of the Capitol in the next 48 hours.

House Democrats, for example, are proposing a corporate tax rate of roughly 26.5 percent, though Manchin and Sen. Mark Warner (D-Va.) have stated that it should not exceed 25 percent. When asked about the House’s higher rate, Warner said on Monday that it “depends on how the pieces all fit together.”

On Monday, a group of House moderates criticized the energy language, claiming that their colleagues’ policies are “targeting the U.S. oil, natural gas, and refining industries.”

And House and Senate Democrats were outraged that the House Ways and Means Committee did not include changes to the Trump-era state and local tax (SALT) deduction cap, which has disproportionately impacted taxpayers in New York, New Jersey, and California.