“Somebody be a little positive. I mean come on. Geez,” Portman told reporters who questioned the deal's chances. He said negotiations were going well: “I just spent all day talking to Democrats and Republicans, all my colleagues, and we’re making progress.”

Still, Portman said the White House has “added some new challenges to the list,” hinting at deep disagreements with Democrats over key policy areas like broadband, water funding, highways, public transit and financing the agreement. With July nearly turned to August, the number of outstanding issues prompted a fresh round of urgency among Democrats, who are worried their agenda could stall without one final push.

Senate Majority Leader Chuck Schumer said he was "fully committed" to passing a bipartisan infrastructure bill this summer, and warned that more foot-dragging could require the Senate to stay in over the weekend or cuts to some of the upcoming August recess. And for a Democratic Party eager to move on to the rest of its agenda before the midterms cloud every decision in Congress, time is running short.

"The bipartisan group of senators has had nearly five weeks of negotiations since they first announced an agreement with President Biden. It's time for everyone to get to yes and produce an outcome," Schumer said on Monday afternoon.

In interviews on Monday, there were no signs among senators that anyone was willing to walk away from the table after investing so much time in the discussions to spend nearly $600 billion in new money on roads, bridges, broadband and climate infrastructure. One Senate Democrat privately assessed that the two parties had come too far to bail on the bipartisan effort.

“I anticipate doing whatever it takes to get the job done,” asserted Sen. Joe Manchin (D-W.Va.).

Schumer also challenged Republicans over whether they would "follow the absurd demands of a disgraced former president" and abandon the deal. He called on the GOP to "ignore former President Trump,” who asked Republicans to drop discussions with Democrats altogether.

As bipartisan negotiators aim to finalize an agreement, Trump said that Senate Republicans “are being absolutely savaged by Democrats on the so-called ‘bipartisan’ infrastructure bill” and urged them to wait until they take back the Senate in 2022 to “regain a strong negotiating stance.” Trump tried unsuccessfully to cut a deal with Democrats on infrastructure during his presidency, sidelining negotiations once his impeachment investigation began.

Schumer's urgency and Trump's taunts reflect a state of negotiations more dire than it's been in a month, so much so that the GOP sent out a list of areas where that Democratic offer broke from previous agreements among the bipartisan senators writing the bill on Monday afternoon. It is the latest in a running list of bleak signs for the talks ahead of another pivotal week of negotiations in the Senate.

“It all seems easy until you get to the final details and they’re never as easy as you think they’re going to be,” said Sen. Roy Blunt (R-Mo.)

Although the bipartisan group and the White House announced an agreement last month on a bipartisan framework, translating it into legislative text is proving difficult. Schumer wants to pass the bipartisan bill and begin the process for Democrats’ $3.5 trillion social spending package before the Senate leaves for the August recess.

Even if senators can cut a deal and get it on the floor, it still needs to go through floor consideration — which could take days if not weeks. Senate Minority Whip John Thune (R-S.D.) warned that his party would want the option to offer as many amendments to the bill as possible, illustrating pent-up demand to try and modify a bill that Biden is certain to sign.

Democrats and the White House on Sunday night made an offer to Republicans that proposed a deal on highway and public transit funding, as well as several other unresolved areas. That offer was intended to address all outstanding disputes — and was immediately rejected by Republicans.

A GOP source familiar with the negotiations said Schumer and Biden were trying to “reopen numerous issues the bipartisan group had already agreed to” and urged both to show more flexibility. Two additional sources close to the talks, one in each party, confirmed the perilous state of negotiations on a signature priority of Biden.

Each blamed the other side for reopening debate on items once considered settled, with a Democrat familiar with the negotiations saying that “it takes a lot of chutzpah for Republicans to make accusations about keeping words” after they walked away from a key financing pillar of the agreement: increasing IRS enforcement to raise money.

White House press secretary Jen Psaki said she is “confident” an agreement can be reached. But many struck a more dour tone.

“Keep in mind that the longer it goes [Senate Minority Leader] Mitch McConnell’s hand gets stronger and he’s able to figure out this part and that part in trying to peel off one of the Republican senators here and there,” warned Senate Majority Whip Dick Durbin (D-Ill.) on Monday.

The bipartisan group of lawmakers hoped to reach a final agreement by early this week after a vote to advance undrafted legislation failed last week. But that appears unlikely, with several issues outstanding. While transit seems to be the biggest sticking point, provisions on both broadband and the bill’s finances are also not resolved.

A Democratic source familiar with the bipartisan discussions said that Democrats’ counteroffer included accepting the GOP proposal for highways in exchange for the Democratic proposal on transit. But Republicans dispute that characterization. A GOP source familiar with the negotiations said the choice isn't binary and that the GOP offer on transit "was met with silence for three days.”

Funding for water infrastructure also remains unresolved, according to a Democratic source familiar with the talks, who accused Republicans of backing away from the original agreement. That source said that Sen. Mitt Romney (R-Utah) had reneged on a deal and "proposed something completely unworkable."

A spokesperson for Romney called that "laughably false" and said Schumer is seeking $15 billion more than a previous agreement.

Senate Environment and Public Works Chair Tom Carper (D-Del.) and Sen. Tammy Duckworth (D-Ill.) both raised concerns about the funding last week. The snafu illustrates the tricky challenge the group of rank-and-file senators led by Kyrsten Sinema (D-Ariz.) and Portman has in navigating around committee chairs.

Eleven Senate Republicans wrote Schumer last week to tell him they’d be ready to move forward as soon as Monday, provided the bill was mostly completed and its finances were in order. Neither condition was met as senators convened on Monday afternoon.