Sen. Joe Manchin III (D-W.Va.) has voted with the Trump administration more than any other Democrat in Congress. (Andrew Harrer/Bloomberg News)

A few hours before Republicans secured the votes they needed to advance a tax-cut bill to the Senate floor, Sen. Joe Manchin III (D-W.Va.) gathered more than a dozen Democratic colleagues to explain why none of them could vote yes. Manchin, who has voted with the Trump administration more than any other Democrat in Congress, described a repetitive drama that had played out for months. He’d sit for productive conversations with the Trump administration, then watch as none of his ideas appeared in the Republican product.

“No tax breaks for the rich? I said that’s great,” Manchin said. “Helping the middle class, working class? That’s great. That’s not what we’re seeing.”

Tuesday’s Democratic drama, from party leaders snubbing the White House to activists shouting and jeering at Senate Budget Committee members, did not slow down the tax bill. It also emphasized just how little pressure vulnerable Democrats felt to back the GOP’s ever-morphing product. Republicans, who started the 2018 midterm cycle optimistic about unseating many of the 10 Democrats whose states went for Donald Trump in the 2016 presidential election, appear headed for a partisan shutout.

They’ve been making the most of it. For months, state Republican parties and outside groups have attacked the “Trump state” Democrats preemptively, warning voters that the Democrats stand between them and “tax relief.” The president, his media team and Republican senators have warned Democrats that voting no would put them on the wrong side of a winning issue.

“We’ll hold out hope that Democrats in the Senate want to put partisan politics aside and put the people of this country first,” White House press secretary Sarah Huckabee Sanders said this month.

For a short while, some progressives worried that Manchin, and perhaps Sen. Heidi Heitkamp (D-N.D.) and Sen. Joe Donnelly (D-Ind.) would break and give Republicans some bipartisan cover. Those three Democrats, widely seen as the most vulnerable in 2018, had backed Neil M. Gorsuch’s Supreme Court nomination; they had played ball with Trump when he delivered speeches in their states, with Heitkamp even joining him on Air Force One. For weeks, they participated in talks with the White House, reporting back positively on what they’d discussed.

But to progressives’ delight, the White House never brought the red state Democrats on board. The problem was simple: White House negotiators would sound open to what the Democrats suggested, and then House and Senate Republicans would rush ahead with completely different ideas.

“There’s always a reason to watch when one of those White House meetings is called, but we never saw a serious proposition that could attract Democratic senators,” said Tim Hogan, a spokesman for the anti-tax-cut group Tax March. “I think it shows so clearly that this tax bill has nothing to do with the middle class. Every Democratic senator knows that this bill would further rig the system in favor of the 1 percent — there’s just no appetite for that. And at no point was there an effort to dangle anything appealing to any of them.”

Republicans’ actual proposals proved to be so unpopular that Democrats felt little pressure to bend. Republicans and outside groups presented reform as a clear winner, pointing to polls that showed majorities of Americans in support of “tax reform.” Democrats got relatively little airtime to make the counter-argument; in the past two weeks, no Democrat was invited on the three main Sunday talk shows to discuss taxes.

Recent polling, however, found that the tax-cut bill that was working through Congress was broadly unpopular, with only a few isolated ideas, such as doubling the standard deduction, finding favor with voters. A Quinnipiac poll released Nov. 15, and frequently cited by Democrats, found just 25 percent of voters in favor of the plan and only 16 percent confident that it would cut their taxes.

“When I took this job, I never expected that Republicans would let a tax bill include middle-class tax increases,” said T.J. Helmstetter, a spokesman for the progressive Americans for Tax Fairness. “There’s no pressure to support that.”

Other Democrats have learned from experience that the price for opposing a tax cut is low, and the reward for backing it is dubious. In 2001, when George W. Bush pushed his first tax cut through the Senate, 12 Democrats voted with Republicans — a major victory over the slim Democratic majority. Yet two of the Democrats who backed the tax cut, Missouri’s Jean Carnahan and Georgia’s Max Cleland, went on to lose reelection bids in 2002.

There were also other factors at play in the 2002 election, with Bush enjoying high approval ratings and an ongoing debate about whether to invade Iraq. But Democrats learned a similar lesson in 2010, when they got no apparent electoral benefit from passing payroll tax cuts as part of the 2009 stimulus package. Republicans in that election hammered Democrats relentlessly on the idea that they had increased the overall cost of living, in part by cutting the growth of Medicare spending.

By opposing this year’s tax cuts, Democrats expect to run against Republicans’ own cuts to Medicare spending. And Tuesday afternoon, as the president made a show of Democratic leaders deciding to snub his meeting, he demonstrated how little the Democrats’ votes meant to the tax bill.

“We had a unanimous vote, from the Republican side at least,” Trump said.