WASHINGTON — President Trump touched off a sharply partisan debate over some of the most divisive issues in American life on Wednesday as he cited this week’s terrorist attack in New York to advance his agenda on immigration and national security while assailing Democrats for endangering the country.
A day after an immigrant from Uzbekistan was arrested on suspicion of plowing a pickup truck along a crowded bicycle path in Manhattan, killing eight people, Mr. Trump denounced the American criminal justice system as “a joke” and “a laughingstock,” adding that he was open to sending “this animal” instead to the American military prison at Guantánamo Bay, Cuba.
Shortly before midnight, the president took it a step further, posting a message on Twitter declaring that the suspect, Sayfullo Saipov, should be executed. “NYC terrorist was happy as he asked to hang ISIS flag in his hospital room,” he wrote, referring to the driver’s reported interest in the Islamic State extremist group. “He killed 8 people, badly injured 12. SHOULD GET DEATH PENALTY!”
Presidents are typically advised never to weigh in on pending criminal cases because such comments can be used by defense lawyers to argue that their clients cannot get a fair trial — especially when the head of the executive branch that will prosecute the charges advocates the ultimate punishment before a judge has heard a single shred of evidence at trial. But Mr. Trump has disregarded such advice in other instances, as well.
The president’s vocal response to the attack framed the emerging politics of the case. While the White House deemed it unseemly to have a policy debate on gun control immediately after the massacre in Las Vegas last month, Mr. Trump was eager on Wednesday to have a policy debate on immigration. He pressed Congress to cancel a visa lottery program that allowed the driver into the country, attributing it to Senator Chuck Schumer of New York, the Democratic leader, and called Democrats “obstructionists” who “don’t want to do what’s right for our country.”
“We have to get much tougher,” the president told reporters. “We have to get much smarter. And we have to get much less politically correct. We’re so politically correct that we’re afraid to do anything.”
A moment like this was almost inevitable since Mr. Trump took office and sought to ban visitors from select countries with Muslim majorities. The terrorist attack in New York on Tuesday was the first by a foreign-born assailant on American soil since Mr. Trump’s inauguration, and few were surprised that he saw it as vindication for his tough-on-immigration approach.
It also provided fodder for him to shift the public focus away from the special counsel investigation that unveiled criminal charges against three former campaign aides this week. But in an interview with The New York Times on Wednesday, Mr. Trump adamantly denied being concerned about the indictments.
“I’m not under investigation, as you know,” he said in a brief telephone call. Pointing to the indictment of his former campaign chief, Paul Manafort, the president said, “And even if you look at that, there’s not even a mention of Trump in there.” Noting that Mr. Manafort was charged with financial crimes stemming from his lobbying business, the president added: “It has nothing to do with us.”
Mr. Trump, a lifelong New Yorker, wasted little time Wednesday morning assigning fault for the attack along the bicycle path. “The terrorist came into our country through what is called the “Diversity Visa Lottery Program,” a Chuck Schumer beauty,” he wrote on Twitter.
Mr. Schumer responded from the floor of the Senate, noting that after the attacks of Sept. 11, 2001, President George W. Bush brought Mr. Schumer and Hillary Clinton, then the other Democratic senator from New York, to the White House to demonstrate national unity.
“President Trump, where is your leadership?” Mr. Schumer asked. “President Trump, instead of politicizing and dividing America, which he always seems to do at times of national tragedy, should be bringing us together and focusing on the real solution — antiterrorism funding — which he proposed to cut in his most recent budget.”
At a news conference updating the public about the attack, Gov. Andrew M. Cuomo of New York chided Mr. Trump for his Twitter posts, saying they “were not helpful,” were not “even accurate” and “tended to point fingers and politicize the situation.”
“You play into the hands of the terrorists to the extent that you disrupt and divide and frighten people in this society,” said Mr. Cuomo, who is a Democrat. “And the tone now should be the exact opposite by all officials on all levels. This is about unification, this is about solidarity.”
At his own public appearance later in the day, Mr. Trump took aim again at the diversity lottery visa program. “Diversity lottery — sounds nice,” he added. “It’s not nice. It’s not good. It hasn’t been good. We’ve been against it.”
Responding to questions by reporters, he said he was open to transferring Mr. Saipov from civilian courts into the military system set up for foreign terrorists.
“I would certainly consider that,” he said at the beginning of a cabinet meeting. “Send him to Gitmo, I would certainly consider that, yes.”
Likewise, he vowed to toughen prosecution and punishment of terrorists without specifying how. “We need quick justice and we need strong justice, much quicker and much stronger than we have right now,” Mr. Trump said. “Because what we have right now is a joke and it’s a laughingstock.”
His later call for the death penalty stemmed from news that Mr. Saipov expressed loyalty to the Islamic State even as he recovered from a gunshot wound by a police officer who stopped his rampage. In a criminal complaint filed on Wednesday, the F.B.I. said Mr. Saipov “requested to display ISIS’s flag in his hospital room and stated that he felt good about what he had done” during an interview with law enforcement officers.
No one arrested on American soil has ever been sent to Guantánamo Bay, and no one captured on foreign soil has been sent there since 2008. Transferring the suspect from New York would raise a host of thorny constitutional and legal issues, and Mr. Trump seemed to be speaking off the top of his head since federal prosecutors later moved to process the suspect in civilian courts.
Asked later about his comment on Guantánamo, Sarah Huckabee Sanders, the White House press secretary, dismissed it as notional, saying that “he wasn’t necessarily advocating for it, but he certainly would support it if he felt like that was the best move.”
By the end of the day, the president came under criticism from conservative allies for not declaring Mr. Saipov an enemy combatant, which would have allowed interrogators more freedom to question him without granting him the rights of a civilian defendant. “The Trump administration missed an important opportunity to send a strong message to terrorists and make America safer,” said Senator Lindsey Graham, Republican of South Carolina. “This is a huge mistake. Very sad.”
The diversity visa program cited by Mr. Trump was created in 1990 by a bill supported by Mr. Schumer, passed by bipartisan votes and signed into law by a Republican president, George Bush. Mr. Schumer supported getting rid of the program as part of a comprehensive immigration plan crafted by eight lawmakers and passed by the Senate in 2013. But the plan was blocked in the House by Republicans who objected to other elements they considered amnesty for illegal immigrants.
Senator Jeff Flake, a Republican from Arizona who has broken with Mr. Trump, came to Mr. Schumer’s defense on Wednesday. “Actually, the Gang of 8, including @SenSchumer, did away with the Diversity Visa Program as part of broader reforms,” Mr. Flake wrote on Twitter. “I know, I was there.”
The program creates a class of immigrants called “diversity immigrants” from countries with historically low rates of immigration to the United States. About 50,000 diversity visas are distributed annually, or roughly 5 percent of the total green cards issued by the United States. Nearly 14.7 million people applied last year, meaning less than 1 percent of those who seek such visas receive them.
The program has been a target of conservatives, who proposed eliminating it in legislation endorsed in August by Mr. Trump that would crack down on legal immigration. The legislation would slash legal immigration to the United States in half within a decade by sharply curtailing the ability of American citizens and legal residents to bring family members into the country.
In his remarks, Mr. Trump stressed that he wanted “merit-based” immigration, suggesting that Mr. Saipov was admitted without consideration about whether he had skills that could benefit the United States. In fact, the program requires applicants to have a high school education or be employed for at least two years in jobs approved by the State Department.
Mr. Trump, who during last year’s campaign called for a complete ban on all Muslims entering the United States, has long sought to tighten the borders. He has signed several versions of the travel ban aimed mainly at predominantly Muslim countries even as courts repeatedly intervened.
Uzbekistan was not among the countries targeted for “extreme vetting” but Ms. Sanders said “that may be something that’s looked at.”