After meeting with two centrist Democratic Senators on Wednesday, President Joe Biden took to the airwaves Thursday to remind Americans what exactly his fighting for in his $3.5 trillion legacy bill, the Build Back Better Act.

“It’s a historic middle-class tax cut—cutting taxes for over 50 million families,” Biden said in a speech from the White House East Room. 

While Republicans would “rather protect tax breaks for those at the very top,” Biden charged, “it’s about time that working people got the tax breaks in this country.”

Biden’s working-folks tax cut pitch has obvious political appeal, but it’s also designed to reframe the discussion around the benefits of Democrats’ massive bill rather than letting the package be defined by the daily churn of news stories picking apart every little point of tension among congressional Democrats. Whether it’s the “price tag,” prescription drug pricing, the state and local tax (SALT) deduction cap, the specifics of the tax hikes on wealthy individuals and corporations, procedural disputes, or any other of a panoply of issues—allowing the debate to get bogged down in the minutia threatens the bill with death by a thousand cuts.

Setting the scene for the stakes of the debate, Biden said, “I believe we’re at an inflection point in this country, one of those moments where the decisions we’re about to make can literally change the trajectory of our nation.”

Biden’s ability to rally Democrats around that inflection point will prove crucial to whether he can help Democratic leaders in the House and Senate iron out the differences both within and between their caucuses. To that end, Biden is scheduled to huddle with Speaker Nancy Pelosi and Majority Leader Chuck Schumer later on Thursday. The president also met Wednesday with centrist Senators Joe Manchin of West Virginia and Kyrsten Sinema of Arizona—two of the biggest hurdles to the passage of Biden’s Build Back Better plan. 

Both senators have objected to the overall size of the package, which appears to be something the White House is willing to bend on even though progressive lawmakers are adamantly opposed to going below $3.5 trillion.

As the Washington Post reported, “White House chief of staff Ronald A. Klain said at an event Wednesday that the $3.5 trillion package could be scaled back by cutting down the size of some new programs or trimming the duration of some of the spending.”

“The truth is, the cost of the Build Back Better plan is zero,” Klain added, an effort to remind the Manchins and the Sinemas of the world that fears over deficit spending aren’t even a valid part of the discussion. 

The real argument here isn’t over the debt or deficit. As NBC News reporter Sahil Kapur notes, progressives and centrists disagree over the size of the tax hikes and the resultant amount of spending/investment based on that.

Sinema’s spokesperson called the meeting with Biden “productive,” but her own behind-the-scenes productivity is dubious at best. 

The Post reports that Sinema has devoted much of her energy to ensuring “that matters that were negotiated out of the bipartisan infrastructure bill—additional transit funding, for instance—do not reappear in the Build Back Better bill.” In other words, she’s working to give Senate Republicans ultimate veto power over what’s included in a Democratic bill designed to address progressive priorities.   

As if that weren’t bad enough, Sinema is also “exploring ways to ‘means test’ some programs”—every Republican lawmaker’s dream provision. 

One other particularly notable hurdle is the timing between the House and the Senate. The House will be ready to vote on its finalized version of the $3.5 trillion Build Back Better bill before the Senate. Still, some Democrats are squeamish about voting on such a major piece of legislation if some of its elements are ultimately omitted from the Senate side. It simply creates an opening for more needless attack ads from Republicans next year. 

Pelosi agreed to begin consideration of the trillion-dollar bipartisan infrastructure bill by September 27. But ideally, she would be able to complete work on the $3.5 trillion Democrats-only bill first—thereby satisfying progressives and greasing the skids for their cooperation on passing the more moderate infrastructure bill.