Senate Minority Leader Charles E. Schumer (D-N.Y.), on Capitol Hill, on Jan. 24. (Melina Mara/The Washington Post)

About every two weeks, Senate Minority Leader Charles E. Schumer keeps an important dinner date with five of his colleagues, and they’re not the five most senior members of the Senate or even his closest advisers in his new job.

They are “the Big Five,” as Schumer calls them: five moderate Democrats representing states that President Trump won who are likely to face the most difficult reelection fights next year.

Given the stakes, “We have to protect these people,” Schumer (D-N.Y.) said of his targeted colleagues. “And sometimes we’re going to have to do things to help them. We all have to watch each others’ backs.”

Here’s the rub: Alongside Schumer’s concern for these vulnerable Democrats is a sudden burst of energy on the left, not only to express deep-rooted anger at Trump but growing impatience with congressional Democrats. If they don’t push far enough, the liberals will be angry. If they push too far, they risk losing seats.

They also risk provoking Republicans. If Democrats try to block Judge Neil Gorsuch, for instance — Trump’s nominee for the Supreme Court — Republicans have the ability to eliminate the filibuster, which would enable Gorsuch’s confirmation on a simple-majority vote.

Senate Minority Leader Charles E. Schumer (D-N.Y.) emerges from a lunch with fellow Democrats on Capitol Hill on Jan. 24. (Melina Mara/The Washington Post)

“I’m worried about the Senate coming apart,” said Sen. Bill Nelson (D-Fla.), who faces a multimillion-dollar reelection campaign next year. “If you can’t get anything done and you eliminate the filibuster to remedy that . . . then it becomes just a rote majority vote every time, and the Senate doesn’t function as the Senate has functioned for 240-some years.”

Trump’s attack on the “so-called judge” in Washington state who overturned the administration’s travel ban on people from seven majority-Muslim countries will make things harder for Gorsuch, Schumer said Saturday.

“With each action testing the Constitution, and each personal attack on a judge, President Trump raises the bar even higher for Judge Gorsuch’s nomination to serve on the Supreme Court,” the lead Senate Democrat said in a statement. “His ability to be an independent check will be front and center throughout the confirmation process.”

The situation for Democrats is so intense and personal that Schumer and House Minority Leader Nancy Pelosi (D-Calif.) were taunted by protesters during a rally on the steps of the U.S. Supreme Court on Jan. 30. Back in New York — where Schumer won reelection last fall with 70 percent of the vote — protesters recently rallied near his Brooklyn home, chanting curse words that rhyme with his nickname, Chuck.

All of it puts Schumer in a pretty tight squeeze trying to protect a diminished minority caucus, support the far left and at the same time temper expectations of what Democrats can do.

Schumer has another top goal, as well: to keep Trump at his already historically low approval ratings for a new president.

Senate Minority Leader Charles E. Schumer (D-N.Y.) is surrounded by his leadership team and journalists at the U.S. Capitol on Jan. 31. (Melina Mara/The Washington Post)

“The number one thing that’s going to determine whether we win or lose? If Trump’s at 35 percent we could take back the Senate,” he said. “If Trump’s at 55 percent, we could lose the whole ball of wax. So part of my job is to make sure that we don’t let Trump get away with stuff.”

Schumer said he believes that his job will be made easier by Trump.

“His rhetoric is staying populist, but his activities — if you look at the Cabinet, if you look at so many things they’ve done — they’re hard right,” Schumer said. “Immigration, some of the executive orders, and very little populism. Not a thing to appeal to the economic interests of working people.”

Schumer said he believes that Trump is “trifling with the Constitution,” and as a result, he said he thinks Democrats can make the impending battle over Gorsuch’s nomination into a “Trump referendum.” But they also risk galvanizing conservatives who favor the federal appeals court judge — and given how many within their party are vulnerable next year, they may not have the votes for a filibuster.

Republicans who know Schumer well are watching closely, struck by how quickly his caucus embraced combative tactics in recent weeks to stall the confirmation of Trump’s Cabinet secretaries. In a Republican-controlled chamber, where the rules no longer allow Democrats to filibuster Cabinet nominees, Democrats tried slowing things down by burying nominees in hundreds of written follow-up questions, boycotting committee-room votes to protest their qualifications or Trump’s latest actions, and then forcing the Senate to stretch out consideration of each pick.

Sen. John Cornyn (R-Tex.), the No. 2 Republican, described the Democratic strategy as “spiteful” and “an irritant.”

“My hope is we’ll get past that,” he said.

Sen. John McCain (R-Ariz.), who has worked with Schumer on some of the Senate’s most ambitious legislation, said, “I’m pretty confident that he’ll be the result-oriented guy that I’ve known for many years. But right now, as you know, they’re angry and upset.”

McCain said he worries that Republicans who don’t know Schumer will react more combatively to Democrats and pressure Senate Majority Leader Mitch McConnell (R-Ky.) to change Senate rules.

The New York Democrat is adjusting to his new second-floor office suite in the U.S. Capitol, with sweeping views of the Mall and downtown Washington, including Trump’s new hotel. He’s still figuring out where to hang paintings on loan from Olana, the historic home and studio of the famed Hudson River School painter Frederic Edwin Church; how to use the remote for his flat-screen television; and how to spark flames in the fireplace.

“Look at that fire,” he said in an interview Thursday, pointing at the flames during the interview. “All done by a kid from Brooklyn who never had a fireplace — because of the beauty of starter logs.”

With no national leader of the Democratic Party, Schumer has narrowed his focus to the most pressing matters facing the Senate and his party. He’s keeping his commitment to visit all of New York’s 62 counties each year, but he said most of it will be during the summer recess. As a senator known for his easy access to the media, Schumer said that he is trying to watch his words more.

“One of the changes is everything you say, people pay attention to,” he said. “That didn’t happen three months ago. I’ve got to learn that.”

Twenty-five senators that caucus with Democrats face reelection next year — 10 of them in states that Trump won in November, meaning Democrats could lose even more ground next year.

The “big five” dinner dates — at least for now — are Sens. Joe Manchin III (W.Va.), Heidi Heitkamp (N.D.), Joe Donnelly (Ind.), Jon Tester (Mont.) and Claire McCaskill (Mo.). Schumer aides were reluctant to share more details, but aides to some of the senators confirmed they’re meeting regularly, usually dishing strategy over plates of Chinese food.

Many Democrats credit Schumer as a more inclusive leader than his predecessor, Harry M. Reid of Nevada, whose top-down, iron-fist, combative approach upset younger, ambitious senators, as well as the kinds of moderates facing reelection next year.

After Trump’s executive order banning some foreign nationals from entering the United States incited protests last weekend at the nation’s airports, Sen. Chris Murphy (D-Conn.) used Twitter to blast Republican colleagues for staying mostly silent. The next morning, Schumer called him to discuss potential legislative proposals.

“I talk to Chuck almost every day — and I’m not a committee chair,” Murphy said. “He’s really empowered a lot of newer and younger members.”

While much of the public action has involved confrontation with Trump’s nominees, behind the scenes Schumer and his team have been taking stock of what went wrong in the 2016 election. He admitted that the party’s economic agenda the past four years has been bland; he said he’s working on assembling a populist message that will appeal to working-class, white voters, as well as minorities.

“If we have a strong economic message and platform and policy, then we can unite the disparate elements of the Democratic Party,” he explained. “People have said, ‘Who are you going to go for? The old Obama coalition or the blue-collar people you lost?’ A strong populist, strong economic message unites both. And that’s why I think I’ll be able to get from Bernie [Sanders] to Joe [Manchin].”

Schumer has been so consumed by the fate of his party that he spent more than four hours at a recent Women’s March in New York, polling people in the crowd.

“Twenty percent had not voted and another 10 percent had voted for a non-Hillary [candidate],” including Trump, he said.

The fresh wave of liberal activism in the streets is “terrific,” he said. “Do some of them throw some brickbats and things? Sure, it doesn’t bother me.”

“They’re out there and active and caring, and that is 90 percent of the battle,” he said. “Our biggest problem in 2016 and 2014 was apathy. Now, will it be a challenge to try to channel it into productive ways? Yes, but that’s a process that will take several months.”

The morning after Election Day, Schumer described himself as “destroyed” by Hillary Clinton’s loss to Trump. He said he consoled his grown daughters by singing them verses from a song by the Shirelles, “Mama Said.”

“My eyes are wide open / But all that I can see is / Chapel bells are callin’ for everyone but-a me / But I don’t worry ‘cause, / Mama said there’ll be days like this”

“I knew that if Hillary won and I was majority leader that I’d have fun and I’d get more good things done,” Schumer said. “But this job is more important. And that’s how I feel.”