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The Trump administration wants to know what programs would be affected if the government shutdown continues for weeks longer, a senior Office of Management Budget official has told NBC News.

The administration has asked agency leaders to provide a list of programs that could be affected if the shutdown — already the longest in the U.S. history — goes on for weeks longer, the senior official said.

“Prudent management means planning and preparing for events without known end dates," the official said. "As OMB continues to manage this partial lapse in appropriations, unfunded agencies are being asked to continue to share with OMB an ongoing list of programs that could be impacted within the coming weeks."

The request was first reported by The Washington Post. Acting White House chief of staff Mick Mulvaney told agency leaders he wants to know what high-impact programs would be jeopardized if the shutdown lasts into March or even April, and he wants the list by no later than Friday, the newspaper reported, citing people familiar with the directive.

Economists have told NBC News that an extended government shutdown could be catastrophic for the economy — as well as for the almost 40 million Americans who would lose food stamps, two million people who could lose rental assistance and the 800,000 federal workers and estimated 1.2 million contractors who aren't getting paychecks.

Protesters arrested in DC

Hundreds of already frustrated and struggling federal workers demonstrated Wednesday in Washington, D.C., urging senators to stop sitting on the sidelines and get the government going again.

The workers held a silent protest in the Hart Senate Office Building for 33 minutes — one minute for every day they've gone without pay since the shutdown began. Many held paper plates with messages scrawled on them, like "hostage," "federal workers are going hungry" and "please let us work."

The protest then moved to the Russell Senate Office Building, where 12 demonstrators, including several union leaders, were arrested outside Senate Majority Leader Mitch McConnell's office.

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"They were demanding a meeting," one of the event's organizers, National Federation of Federal Employees spokesperson Brittany Holder, told NBC News.

The Kentucky Republican was also targeted by protesters in his home state. About three dozen workers demonstrated outside of his office in Lexington — and police were called on them when they tried unsuccessfully to present his office with letters describing the hardships the shutdown has forced them to endure.

The lack of a paycheck "is causing a lot of heartache and trouble," said Paula Metcalf, who works for the Census Bureau in Jeffersonville, Indiana. Metcalf said she has medical issues that she can't afford to address.

"I need a lot of medicine, and I'm not able to pay the co-pays," she said.

"I blame (President Donald) Trump and I blame McConnell, Metcalf added. "They just need to let us go back to work."

McConnell has kept a low profile during the shutdown, which began on Dec. 22 after Democrats refused Trump's demand to include $5.7 billion in funding for a border wall in a government spending bill. The Senate had already passed a bill to keep the government open that didn't include any funding for the wall.

After a "Where's Mitch?" campaign by freshmen Democrats in the House of Representatives, including Alexandria Ocasio-Cortez, McConnell announced the Senate would hold two votes on Thursday on competing spending proposals. The Republican legislation would reopen the government and add $5.7 in wall funding, while the Democratic version would simply re-open the government until Feb. 8.

Neither measure is expected to pass.

A bipartisan group of five former secretaries of the Department of Homeland Security, including former White House Chief of Staff John Kelly, released a joint letter on Wednesday calling on Congress and the president "to fund the critical mission of DHS."

The letter warned that the longer DHS employees are forced to work without pay, the greater risk they would seek jobs elsewhere.

"High-tech skills – such as information technology and cybersecurity –and law enforcement and security experience are in great demand in the private sector and the Department is facing a real crisis in retaining this workforce week after week," said the letter.

It was signed by Kelly, who was DHS secretary for Trump before becoming his chief of staff; two people who served in that role under President Obama -- Janet Napolitano and Jeh Johnson; and two who headed DHS under President George W. Bush -- Tom Ridge and Michael Chertoff.

In the meantime, in addition to the financial pain, the shutdown is causing unexpected problems.

In one recent example, a network of rescue groups that works with the National Oceanic and Atmospheric Administration to help marine mammals, such as whales and seals, when the animals are in trouble says the shutdown is making it harder for them to do their work.

A poll released Wednesday showed a strong majority of Americans blame Trump for the shutdown, dragging his approval rating to its lowest level in more than a year.

The poll, by The Associated Press-NORC Center for Public Affairs Research, found 34 percent of Americans approve of Trump’s job performance, down from 42 percent in December.