WASHINGTON — When Speaker Nancy Pelosi of California stepped to a microphone last week and pronounced President Trump’s border wall “an immorality,” most Democrats cheered and nodded their heads.
But a few privately grimaced, worried that such stark terminology could make it more difficult for Democrats and Republicans to find their way out of an impasse over border security that has partially shuttered the government for three weeks, deprived about 800,000 federal workers of their pay and increasingly threatens beneficiaries of federal programs.
Democrats, said one Democratic lawmaker from a Republican-leaning district who insisted on anonymity to offer a candid assessment, cannot be seen by the public as calling border security immoral.
The divide illustrates why Democrats are working to focus public attention on the painful costs of the partial government shutdown — vulnerable families going without food assistance, farmers forgoing crop payments, national parks trashed — and Mr. Trump’s recklessness in courting it, rather than delving into the specific details of erecting a barrier on the southwestern border.
While Mr. Trump has launched an elaborate public-relations effort to draw Democrats into a debate over the wall itself — even the material to be used to construct it — Democrats are just as determined to talk instead about a more universally resonant theme: the need to get the government open and functioning while negotiations continue.
It is at the heart of their effort this week to push through the House a series of bills to reopen shuttered federal agencies, including one scheduled for a vote Wednesday for the Treasury Department and Internal Revenue Service among others. They are expected to pass the Democratic-controlled chamber but die in the Republican-controlled Senate.
The goal: to win over more Republicans in the House and raise pressure in the Senate, where on Tuesday, Lisa Murkowski of Alaska became the latest Republican to call for a vote to reopen the government as talks on border security continue.
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For Democrats, newly in control of the House, the shutdown fight has proved unifying, crystallizing a near-universal belief in their ranks that Congress should act as a check on the power of a president who has shown little regard for the law and has used his office to sow fear and misinformation on issues like immigration.
But while they are almost all opposed to the idea of a wall between the United States and Mexico — which is unpopular among a majority of Americans and strongly opposed by Democratic voters, and which has been dismissed as ineffective by border security experts — Democrats are less united about what form of border security they do support.
Some of them, including Senator Chuck Schumer of New York, the minority leader, voted in 2006 for 700 miles of fencing along the border, a position the White House has repeatedly sought to spotlight.
On Tuesday, on the morning of Mr. Trump’s address to the nation on the topic, Representative Steny H. Hoyer of Maryland, the majority leader, did not mention the word “wall” once in 11 minutes of opening remarks with reporters. He then sidestepped a question about the difference between fencing and other border security measures that Democrats have backed in the past and the wall that the president is demanding.
“I didn’t answer it, maybe because I don’t have an answer that I think is a really good answer,” he finally conceded. “Fencing and walls have the same effect. One is supported by a large number of experts, but a large number of experts think neither are that effective.”
The reality is that making a nuanced argument about border security — a highly technical and politically charged issue — is difficult and divisive. Some Democrats have learned that the hard way in recent days.
Representative Adam Smith of Washington, chairman of the Armed Services Committee, seemed to break from Ms. Pelosi’s “immorality” remark during an interview Sunday on ABC’s “This Week” when he tried to explain his past votes for border barriers.
“The wall is not in itself a bad idea, it’s just — it’s been done,” Mr. Smith said. “And what the president has not done is, he has not made the case that on the portions of the border where a wall has not been built, how is a wall going to actually enhance border security?”
Representative Liz Cheney of Wyoming, chairwoman of the House Republican Conference, jumped at Mr. Smith’s remarks: “That’s a very different point than the one that Speaker Pelosi continues to make, which is that a wall is immoral.”
Representative Mac Thornberry, Republican of Texas, noted that there are already physical barriers on about 30 percent of the border. “So, to go from 30 percent to 40 percent is a moral issue? I don’t understand that,” he said.
When Senator Chris Coons, Democrat of Delaware, said this week that Mr. Trump’s recent talk of a wall made of steel slats rather than concrete was “progress,” he quickly clarified that he was not, in fact, buying into the president’s idea.
“I said that it was a minor step,” he told CNN on Tuesday. “I was accepting that steel slats are preferred by the Department of Homeland Security over a concrete wall; I was not saying that I think that we should be pouring billions of dollars into a border barrier.”
Democratic strategists argue that Mr. Trump’s failure to build broad public support for a wall that he has been demanding since the early days of his presidential candidacy has made it easier for Democrats to stake out a unified message.
“Obviously, there are some Democrats who talk about the wall being immoral or inconsistent with American values, but across the spectrum of Democrats, there is an emphasis on the degree to which the wall is waste of taxpayers’ money and irrelevant to addressing the most important challenges we face with regard to immigration in the country,” said Geoff Garin, a Democratic pollster. “Democrats are being helped a little bit by Trump’s specificity in what he’s looking for. He keeps talking about something that is very specific, and is something that more than half of all Americans oppose.”
Nick Gourevitch, a pollster and communications strategist who advised Democrats during the midterm campaign on Mr. Trump’s fear-soaked immigration message, said Democrats are sticking to the simplest and freshest argument they have to appeal to a public that does not focus on the finer points of border security policy.
“The wall is unpopular, and the wall combined with the shutdown is even more unpopular,” Mr. Gourevitch said.
“Most presidents don’t lose in a wave election and then double down on the strategy that got them there,” he added, “but that’s what this president seems to be doing.”