WASHINGTON — President Donald Trump sought Sunday to pressure Democrats amid the threat of a government shutdown, tweeting that the country is susceptible to dangers such as the MS-13 gang without a border wall, and that Mexico ultimately will pay for the construction in some way.

“The Democrats don’t want money from budget going to border wall despite the fact that it will stop drugs and very bad MS 13 gang members,” he posted of the street gang that authorities have said is responsible for killings nationwide, including a quadruple homicide this month in Central Islip.

A spending package must be passed by Friday to keep the government open. The legislative hurdle comes as Trump faces a packed week ahead, which will be punctuated by a Saturday campaign rally in Harrisburg, Pennsylvania, to mark his 100th day in office.

A wall at the southern border — with Mexico footing the bill — was a top campaign promise that Trump now says must be first funded by the United States to expedite the process.

The president and his surrogates said Sunday that Mexico will pay eventually somehow, including via tax credits or trade losses reclaimed by the United States.

“Eventually, but at a later date so we can get started early, Mexico will be paying, in some form, for the badly needed border wall,” Trump tweeted.

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On ABC News’ “This Week,” host George Stephanopoulos noted to Attorney General Jeff Sessions that legislators in border states, including Republicans, don’t support the wall and asked for evidence that Mexico will pay.

“We’re going to get paid for it one way or the other,” Sessions said. As an example, he cited $4 billion a year in erroneous allotted tax credits to “mostly Mexicans” that can be recouped.

He added: “I don’t expect the Mexican government to appropriate money for it, but there are ways that we can deal with our trade situation to create the revenue for it.”

Trump surrogates said Democrats are risking a government shutdown in exchange for insurer funding to keep the Affordable Care Act afloat, while Democratic leaders said GOP supporters of Trump prioritize the border wall over keeping government open.

“One of the biggest priorities during the campaign was border security, keeping Americans safe, and part of that was a border wall,” Office of Management and Budget Director Mick Mulvaney told “Fox News Sunday.” “And we don’t understand why the Democrats are so wholeheartedly against it.”

The Senate’s Democratic whip, Dick Durbin of Illinois, on CNN’s “State of the Union,” said shutting down the government “over this outlandish proposal of a border wall — which we can’t even pay for at this point and is opposed by Democrats and Republicans all along the border” — would be “the height of irresponsibility.”

A senior White House official said Sunday that Trump’s busy week ahead includes outlining principles for his tax code overhaul plan; introducing his Victims of Immigrant Crime Engagement office, or VOICE; and executive orders benefiting veterans and moving the country toward energy independence.