With the shutdown heading into its third day, they were feeling the heat and finding it hard to control the messaging war. Voters in Florida, Michigan, Ohio, Pennsylvania and Wisconsin were getting Republican robo-calls saying Democrats had "prioritized illegal immigrants over American citizens."
So the Democrats decided to take a deal they had turned down only the night before — a less-than-airtight assurance by Senate Majority Leader Mitch McConnell (R-Ky.) that "it would be my intention" to consider legislation that would address those immigrants in the coming weeks, but only if the government were reopened.
"There's a practical question of, 'Are you going to achieve more by holding out, are you going to get anywhere?' " asked Sen. Angus King (Maine), an independent who caucuses with the Democrats. "[Schumer's] assessment was, this was a positive step forward and to hold out further, you wouldn't get any more."
Federal shutdowns are a tactic that has been tried with some regularity over the past quarter-century.
This time, it was the Democrats' turn to learn what Republicans have before them: First, that bringing the government to a halt is not an advantageous way for the opposition to force through the policy objectives it has not been able to achieve through legislating. And second, that the party that holds the White House has the upper hand.
Polls consistently show that a large majority of the public is sympathetic to the plight of the hundreds of thousands of immigrants who were brought to this country illegally by their parents, and opposes President Trump's decision to end the Obama-era program, Deferred Action for Childhood Arrivals (DACA), that shielded them from deportation. If it is not renewed by March, the "dreamers" face the prospect of being forced to leave the only country many have ever thought of as home.
But what the Democratic senators were sensing was something else that shows up in the polls: Most voters do not want to see the government shut down over immigration. And the causes that are articles of faith with the Democrats' liberal and ethnically diverse base can alienate many voters in conservative, largely white battleground states.
After the Democrats' huddle, Schumer went to the floor and relented. He declared that McConnell's statement was a "commitment" and warned the GOP leader to "abide by this agreement" or else risk breaching the trust of lawmakers in both parties.
Trust, however, is not a currency that is trading at a high value these days in Washington politics.
A flood of social media fury was directed at Schumer for a "cave" by "weak-kneed, right-of-center Democrats," as the Progressive Change Campaign Committee framed the Democrats' move. Outraged liberals moaned that Democrats had won nothing but a fig leaf to cover the fact that they had broken down.
OFA, the political remnant of Barack Obama's presidential campaigns, issued a statement: "Let's be clear: This stopgap measure is not a solution. It's merely a band-aid for a self-inflicted wound that remains untreated."
"I do not see how a vague promise from the Senate Majority Leader about a vague policy to be voted on in the future helps the Dreamers," said Rep. Luis V. Gutiérrez (D-Ill.), one of the party's most prominent immigration advocates.
Immigrant advocates and liberals were frustrated in December when Democrats supported the last short-term spending bill with nothing in return for the dreamers. Democratic leaders tried to quiet their concerns by promising to make their stand on the issue in January.
The shutdown exposed the challenges facing congressional Democrats daily: how to wrangle victories while in the minority and keep the party's base energized ahead of the November elections.
Unlike conservative Republicans who led a 2013 government shutdown, Democrats have no antipathy for the federal government and its services — and they squirmed this week once they began to be blamed by Republicans when agencies were shuttered.
"I just think our job is to make sure government works for people and their lives get better, and that's what I tried to do," said Sen. Joe Donnelly (D-Ind.), an at-risk incumbent who had called for days for the shutdown to end.
Democrats tried to blame the impasse on Republicans, noting that they control both the White House and Congress.
But their own polling revealed that a shutdown could be a bigger political problem for Democrats fighting for survival in conservative states.
A survey of red-state voters conducted last month by the Senate Majority PAC, which aims to elect Democrats to the Senate, showed that 48 percent of respondents would blame them for a shutdown, compared with 39 percent who said the fault would lie with Trump and the Republicans.
Other Democrats also felt uncomfortable with the shutdown being defined purely as an exercise to address the concerns of the dreamers. Beginning Sunday and into Monday, Senate Democrats began to try to tweak the terms of the debate and spoke of other issues driving their stance, such as efforts to secure disaster aid or expand community health centers.
Searching for silver linings, some argued that what their liberal base saw as capitulation was actually a sign of something the Senate has not experienced in years — bipartisanship.
After the government shut down, "there was a large group, 25 senators almost evenly divided between the parties, that immediately went to work and fixed this and that's the way this place is supposed to work. So I'd rather dwell on that than what might have been had we not gotten this done," said Sen. Claire McCaskill (D-Mo.), who is battling for reelection in a state that Trump won by nearly 19 percentage points in 2016.
Whether that kind of cooperation can continue is another question. Much will hinge on whether McConnell follows through on his pledge to deal with the immigration issues that brought the two sides to their three-day standoff.
"Now comes the test, the real test, as to whether we can get this done, whether we can be the Senate again, whether we can return to regular order on the floor and constructively have a debate," said Sen. Richard J. Durbin (Ill.), the Senate minority whip. "For some of you, it will be the first time you've ever seen it. But believe me, it's worth the price of admission, all it took for you to come to the United States Senate."