WASHINGTON — Impeachment, meet government shutdown.

With funding for federal operations set to expire Nov. 21, the political class here is beginning to plan for the possibility — or the likelihood, in the eyes of some — that President Donald Trump will shut down the government to try to turn public opinion against House Democrats and their push to impeach him.

"He used it for his almighty wall for the longest shutdown in history, so I don't put anything past him when it comes to this," Sen. Dick Durbin of Illinois, the Democratic minority whip, told NBC News.

It's not just Democrats who have learned that Trump has a tendency to add as many chips to the pile as he can in high-stakes political battles, particularly when things aren't going his way. Right now, according to an impeachment tracker by FiveThirtyEight.com, a plurality of Americans (48.6 percent to 43.3 percent) support removing the president from office.

Trump has a history of seeking dramatic means to alter storylines.

"The Republican leadership is watching this very closely and anything really can happen, and that does give him the ability to express himself and he has done that before," said Ron Bonjean, a former Republican leadership aide in both the House and Senate who assisted the Trump White House with Supreme Court Justice Neil Gorsuch's confirmation hearings. "Could it happen again? Absolutely. And especially when everything is so personal."

Beyond Trump's irritation at the impeachment inquiry, many Republicans see the potential for a shutdown to flip the script on Democrats.

"The administration could use a spending showdown to put the focus back on the issues and the fact that Democrats don't want to pay for national security, border security or restrain wasteful spending," said one former senior administration official who spoke on the condition of anonymity because he was not authorized to speak for the president.

"The longer Democrats drag out this impeachment circus, the less likely Trump has any reason to cooperate with them on appropriations," the source added.

Yet Democrats contend such a move would backfire on Trump because the public would see it as an attempt to help himself at a cost to the country.

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"If some Republicans want to shut down the government because the House is upholding our oath of office and holding President Trump accountable, they'll have to defend that to the American people," Rep. Nita Lowey, D-N.Y., chairwoman of the House Appropriations Committee, said in a statement.

On Capitol Hill, where the Senate is just taking up some of its versions of the annual appropriations bills — the dozen measures that fund the government — there is no realistic hope of the two chambers agreeing to all of them before the deadline.

A big part of the impasse has to do with the long-running fight between the White House and Congress over the president's efforts to fund a border wall between the U.S. and Mexico, but the two chambers haven't even yet reached a deal on how much to money to allocate for each of the dozen spending bills.

Those who want to avoid a government shutdown want to make progress on those bills while passing a measure called a "continuing resolution" that would keep the government operating beyond Nov. 21.

Count the House Democrats — who would face the politically risky prospect of moving forward with impeachment while the rest of the government sat still — in that camp.

"House Democrats refuse to play politics with a government shutdown, and we will pass necessary legislation to keep the federal government up and running," Lowey said.

Lawmakers keep working during shutdowns, and, as is the case with federal agencies, Congress can designate certain staff as "essential" to do the same.

A senior Trump administration official said in an email that the president probably won't shut down the government, but stopped far short of closing off that option.

"The administration expects Congress to do its job to secure the border and pay our troops, but in the event that they are unable to pass full-year appropriations bills, the president is unlikely to oppose a clean temporary funding bill," the official, who declined to be identified, lacking authorization to speak about the issue, said in an e-mail.

Like Lowey, Sen. Richard Shelby, R-Ala., chairman of the Appropriations Committee, doesn't want to see a lapse in federal funding. And he doesn't think it would be a political boon for Trump.

"I've said for years, and I've said to the president, that to shut down the government helps no one, including the administration," he said.

As for whether he's worried that Trump would shut down the government out of frustration with the impeachment process, Shelby stopped short of predicting that the president would avoid that route.

"I would hope not," he said.