WASHINGTON – President Donald Trump blasted Democrats and touted his proposed border wall during a visit to Texas on Thursday hours after making his most explicit threat yet to declare a national emergency and sidestep Congress on the issue.

“If we had a barrier of any kind, a powerful barrier, whether its steel or concrete, we would stop it cold,” Trump said of the drugs, crime and human trafficking he has said are pouring into the United States in what the White House increasingly frames as a "crisis."

Congressional Democrats have rejected Trump's request for $5.7 billion for wall funding, arguing that the physical barrier would not be effective and that the president is manufacturing a crisis to appease his base. The impasse has led to the second-longest government shutdown in U.S. history, now in its 20th day.

Trump's visit to McAllen, Texas, came hours after he laid out in his most explicit language yet a threat to bypass Democrats and declare a national emergency to free up additional funding for the border wall. The Pentagon is preparing options to build barriers along the border if that happens, USA TODAY reported.

"If this doesn’t work out, probably I will do it – I would almost say definitely,” Trump said leaving the White House. “We have plenty of funds if there’s a national emergency.”

In Texas, Trump was briefed by border officials and flanked by families who said their loved ones were killed by immigrants who entered the country illegally.

"They say it’s immoral,” Trump said of Democratic opposition to his proposed wall. “What’s immoral is all the killing that’s taking place."

The president has repeatedly highlighted MS-13 gang violence to suggest that illegal immigration leads to higher crime, but studies generally find immigrants are less likely overall to commit a crime.

Trump later arrived on the banks of the Rio Grande after his motorcade weaved through an industrial area of warehouses and crossed a levee where the wall is proposed to be built.

“This is common sense,” Trump said. “They need a barrier.”

Trump said there would be "a lot of death" on the border if the wall is not built.

Hanging over the visit were questions about whether Trump would declare a national emergency in coming days, a move that would allow him to redirect defense money for a wall but would almost certainly trigger court challenges. An emergency declaration could give Trump an off ramp to reopen the government but continue to fight for the wall.

Trump, wearing a white "Make America Great Again" campaign hat, barely mentioned the possibility of an emergency declaration while in Texas.

The Texas trip came a day after the president walked out of a White House meeting with Democratic leaders negotiating over an end to the partial government shutdown. Hundreds of thousands of federal workers face missing a paycheck Friday. Many of those employees belong to the Department of Homeland Security, which is responsible for securing the border.

During the roundtable law enforcement officials briefed Trump on the ways they are blocking illegal immigration. Officials showed him images of vehicles apprehended at checkpoints smuggling humans and drugs into the country. Another image showed a truck that was floated across the Rio Grande with drugs.

Trump lamented that "the people that are coming in – the criminals, the gangs, the traffickers, the drugs – it’s all crime.” Government data shows that most illegal drugs intercepted at the border come through legal ports of entry.

Trump repeatedly promised during the 2016 campaign that Mexico would pay for the wall, but insisted Thursday that he did not say Mexico would "write a check." Throughout the day,Trump said Mexico would pay “indirectly," a reference to the pending trade deal to replace the North American Free Trade Agreement.

House Speaker Nancy Pelosi and Senate Minority Leader Charles Schumer accused Trump of abruptly leaving a meeting at the White House on Wednesday while administration officials blamed Democrats for negotiating in bad faith. In Washington, Pelosi told reporters that Trump prefers a "soap opera" instead of serious negotiations over border security and ending the shutdown.

“I don’t even know if the president wants the wall,” the California Democrat said. “I think he just wants the debate on the wall.”

Democrats initially proposed $1.6 billion for border security, but none of that money could be used for the kind of wall Trump says he wants.

The effects of the shutdown will only grow with time, even as the White House scrambles to limit the impact. The U.S. Food and Drug Administration reported a slowdown in food safety inspections, airports cited longer lines at security checkpoints, and national parks have been operating for weeks with limited services.

Perhaps a more pressing problem for Trump: Some Republicans have noted the impact on federal employees and a handful of Senate Republicans – including Susan Collins of Maine, Cory Gardner of Colorado and Lisa Murkowski of Alaska – have said they would at least consider a plan to reopen some agencies.

Shortly before Trump boarded Air Force One for his return trip to Washington the House voted on a measure to reopen the departments of Transportation and Housing and Urban Development without additional money for the wall.

Though the measure is unlikely to make it to a Senate vote, a dozen Republicans voted with Democrats on the bill – four more than crossed party lines on a similar bill a day ago.

Contributing: Eliza Collins