Even Sen. Mitt Romney, R-Utah, who has been known to work across the aisle with Democrats, dismissed the price tag as "shocking" and "stunning."
"They’re either going to have to raise taxes enormously or add dangerously to the debt of the country," Romney said Wednesday. "It’s an unthinkable amount of money."
Late Tuesday Senate Majority Leader Chuck Schumer, D-N.Y., announced Democrats had reached a deal on a new spending plan to expand Medicare, address climate change and establish paid family leave. Schumer touted the plan as "exciting" and "transformational" to help middle-class families breathe easier and assist poor families find a pathway to more prosperity.
But within hours, Republicans made clear they wouldn't be supporting the multitrillion-dollar budget reconciliation plan.
Sen. Steve Daines, R-Mont., said Democrats are "foolish" to think a massive tax-and-spend plan would address growing concerns of inflation.
"Democrats and President Biden are on a reckless path that will squander our economic recovery and leave Montana families worse off," Daines said in a statement.
House Budget Committee ranking member Rep. Jason Smith, R-Mo., said now is not the time for more spending.
"The very same day we find out that year over year inflation growth is the highest it's been in over 10 years, Democrats are proposing throwing trillions more of inflation fueled logs on the fire," Smith said. "This is one of the most out-of-touch celebrations I have ever seen. The political leaders in Washington and President Biden are failing the working-class families who can least afford it."
Sen. Mike Lee, R-Utah, raised concerns about adding to the deficit.
"$3.5 trillion in new spending is $3.5 trillion too much and $3.5 trillion we don't have," Lee wrote on Twitter.
Democrats don't need GOP support if they stick together. Biden already forged a roughly $1 trillion bipartisan infrastructure deal with both GOP and Democratic senators that will fund traditional roads, bridges and more.
Meanwhile, Democrats were planning a separate so-called human infrastructure plan to address climate change, health care, education and child care concerns – and to do so without any GOP support necessary through a process called budget reconciliation.
If both proposals pass, it would amount to more than $4 trillion in new spending, which is on par with what Biden had initially asked Congress for. To sell the plan, Biden is visiting the Capitol Wednesday afternoon to lunch with Senate Democrats.
Details of the $3.5 trillion deal are not yet available and it will be a months-long process to usher in the specific spending legislation. But Sen. Mark Warner, D-Va., said Tuesday everything in the new spending plan will be fully paid for – and therefore not adding to the national debt or deficit.
Biden and Democrats had proposed raising taxes on the wealthiest Americans and corporations to pay for the new programs. Schumer confirmed Wednesday that Democrats will look to reverse former President Trump's tax breaks for the wealthy while offering assurances that the middle class will be spared.
"This resolution will make sure that there are no tax increases for families under $400,000 and no tax increases for small businesses," Schumer said. "This is about rebuilding the middle class and creating jobs."
Schumer dismissed the GOP's "phony" concerns about the deficit as outright "hypocrisy" and pointed out that Republicans signed off on raising the deficit under Trump.
"Hello, my colleagues! You raised the deficit by $2 trillion so you could give tax cuts mainly to wealthy people and big corporations," Schumer said Wednesday on the Senate floor. "And now you’re going to complain when we want to help middle-class families, poor families, that there’s a deficit? Give us – and give the American people – a break."
The $3.5 trillion package will focus on jobs, climate and families, Schumer said. He touted the major proposed expansion to Medicare to include dental, vision and hearing coverage, which was championed by Sen. Bernie Sanders, I-Vt.
As long as Democrats stay fully unified, they can pass this with just 51 votes in the Senate with Vice President Kamala Harris's support. The plan isn't as big as the $6 trillion that Sanders and other progressives really wanted, which signals Schumer may be able to get his more moderate colleagues on board.
One famous holdout is West Virginia Democratic Sen. Joe Manchin who has insisted he wanted the new spending to be paid for and that any new tax hike would still keep the United States globally competitive. Manchin said Wednesday he'll "reserve any final judgment" until he can see the details.
Fox News' Jason Donner contributed to this report.