Senate Majority Leader Chuck Schumer (D-N.Y.) dropped a bomb on lawmakers Thursday morning when he outlined an ambitious timeline propelling the bipartisan infrastructure proposal toward floor action next week.

Why it matters: The senators involved have their work cut out for them. There's still a lot of concern about how to pay for the $1 trillion bill, which is key to shoring up Republican support for the measure.

• The group of 10 negotiators huddled for hours Thursday afternoon in a room on the first floor of the Capitol, working to resolve the remaining — and most controversial — sticking points.
• White House officials Steve Ricchetti, Brian Deese and Louisa Terrell joined them roughly an hour in, until they eventually broke and the senators flew home for the weekend.
• The group said it plans to continue negotiating throughout the weekend, with the goal of producing legislative text by the time the Senate returns on Monday.

What they're saying: "The good news is is that we are all still talking. The bad news is we've got a pretty tight timeframe," Sen. Lisa Murkowski (R-Alaska) told reporters.

Between the lines: Axios reported early Thursday that a prominent pay-for initially in the bipartisan framework — a $40 billion infusion to help the Internal Revenue Service with tax enforcement — is being re-thought.

• Sens. Jon Tester (D-Mont.) and Mark Warner (D-Va.) confirmed the group is now discussing potential alternatives to the IRS provision.
• If it's nixed, it's a huge nod to conservatives, many of whom have seen this as the most controversial aspect of a bipartisan bill.
• Sources familiar with the meeting say it may not be dropped in its entirety but peeled back.

Worth noting: Even if the group completes drafting the bill this weekend, it will take days for the Congressional Budget Office to score it — something multiple senators will need before ultimately weighing in.

• It also will take time for the group to sell their colleagues on its key components.
• However, next week's votes are, for now, just procedural — formally kicking off the process to pass the package.
• A final vote on the bill would not come until next Thursday at the earliest.

Why Schumer is doing this: The Senate leader wants to ramp up pressure on lawmakers to finalize their work, Axios has learned.

• They've been negotiating for months, and time is running out if they want to meet their self-imposed deadline of passing it before August recess.
• Yet putting the bill on the floor before both sides are certain it will receive the necessary 60 votes to pass could be catastrophic for its chances.