It’s beginning to feel like 2010 all over again.

Back then, congressional Democrats unanimously supported a sweeping overhaul of the health-care system. But while Democrats haggled over differences (Public option? Single payer? Universal or near-universal coverage?) and Senate Finance Committee Chairman Max Baucus (D-Mont.) waited in vain for GOP cooperation, Republicans made wild claims about death panels, health-care rationing and granny killing. Democrats got clobbered in the year’s midterms.

Now, congressional Democrats agree — unanimously! — that they should pass a roughly $1 trillion infrastructure bill to improve roads and bridges and extend high-speed Internet coast to coast. Democrats agree — also unanimously! — that they should enact the substantial portion of President Biden’s Build Back Better agenda to improve education, health and the planet. But while Democrats squabble over relatively minor differences in how much to spend over how long a time, Republicans have again gone demagogic, raising phony threats about socialism, trillions of dollars of additional debt and a Gestapo-like IRS.

Democrats can’t counter the slander or sell the (broadly popular) plan, because they haven’t finalized the details. And as Democrats dither, Biden is bleeding out; his support has dropped into the low 40s.

Nobody is better at herding cats than House Speaker Nancy Pelosi, but even she is exasperated. On Monday night, she sent a “Dear Colleague” letter to the House Democratic caucus arguing that “difficult decisions must be made very soon” to reduce the $3.5 trillion Build Back Better bill — to a cost that Sens. Joe Manchin III (D-W.Va.) and Kyrsten Sinema (D-Ariz.) can accept. “Overwhelmingly, the guidance I am receiving from Members is to do fewer things well,” Pelosi wrote, suggesting that some programs would be struck entirely.

But Tuesday morning, Pelosi appeared to reverse course, telling reporters that “some members have written back to me and said, ‘I want to do everything,’ so we’ll have that discussion.” She suggested that programs would be allowed to sunset — “cutting back on years” — thereby reducing the 10-year cost.

This is one of those times that proves true the adage of the great early 20th-century humorist Will Rogers: “I don’t belong to any organized political party. I am a Democrat.”

In fairness to Pelosi, it’s not either/or: Democrats, I’m hearing, will eliminate some plans and phase others out early in hopes that they will prove popular and future Congresses will renew them. Far more important than the mechanics is the timing. Democrats don’t have a moment to spare.

As they waver, the voters are turning against them, and the authoritarians are waiting in the wings. On “Fox News Sunday,” Louisiana’s Steve Scalise, the No. 2 Republican in the House, refused repeatedly to acknowledge that the presidential election hadn’t been stolen by Biden. If Biden’s approval numbers stay where they are, Congress will end up back in Republicans’ hands, positioning them to be able to overturn the will of the people in 2024.

House progressives have publicly acknowledged they’ll reduce their demands for the Build Back Better package to a range between $1.9 trillion and $2.2 trillion; Sen. Bernie Sanders, the Vermont independent, has said as much privately, I’m told. That’s a huge concession. Now it’s time for Biden to hammer out a final agreement with Manchin. (Democrats are hoping Sinema will sign on after Manchin does; she has been so erratic that negotiations with her are futile.)

The ultimate details are less important than passing both bills. Democrats could then answer the GOP’s fearmongering with specifics: what size tax breaks families will get, who can go to community college tuition-free, and all without adding to the debt.

Democrats can at that point turn the focus to the Republicans’ anti-vaccine histrionics, the cruel abortion ban in Texas and the perpetuation of the “big lie” about the 2020 election. Combined, these three issues have angered suburban voters nearly to 2018 levels — potentially lifting Democrats in 2022.

But until Biden can pin down Manchin, the bleeding will continue.

At Pelosi’s news conference on Tuesday, CBS’s Nikole Killion told the speaker that the latest CBS News poll found that only 10 percent of Americans know many specifics about the Build Back Better package and that most “don’t know anything at all.”

Pelosi, arguing that “whatever we do, it will be transformative,” told Killion that “whether [Americans] know it or not, they overwhelmingly support it” — a phrase uncomfortably close to her 2010 remark about the Affordable Care Act: “We have to pass the bill so that you can find out what is in it.”

It didn’t work then, and it won’t work now. But history doesn’t have to repeat itself. If Biden can pin down Manchin — now — the impact of the new programs will be felt before next year’s midterms. Democrats would be able to parry the Republicans’ demagoguery with results.