House Minority Leader Nancy Pelosi said Wednesday that Republicans have "no excuse" to shut down the government under their watch since they control both the White House and Congress.

"With a Republican House, Senate and Administration, Republicans have absolutely no excuses for threatening America's families with a destructive and pointless government shutdown," the California Democrat said in a statement.

Her comment comes after President Trump on Tuesday night threatened a government shutdown over funding for his border wall after the crowd began chanting, "Build that wall!"

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"Build that wall," Mr. Trump said. "Now the obstructionist Democrats would like us not to do it. But believe me, if we have to close down our government, we're building that wall."

But Democrats, Pelosi reiterated, would never support funding for the wall, which the president had originally promised would be paid for by Mexico.

"President Trump's multi-billion dollar border wall boondoggle is strongly opposed by Democrats and many Republicans," Pelosi said. "Democrats will stand fast against the immoral, ineffective border wall and the rest of Republicans' unacceptable poison pill riders."

The government last shut down in October 2013 for 16 days. Experts suspect that the negotiation over the wall is more likely to take place in December than next month, but anything can happen.

Congress must pass a new government funding bill by Sept. 30 to prevent a shutdown on Oct. 1, which is when fiscal 2018 begins. In previous years, because of the limited amount of time on Capitol Hill in September, lawmakers have been forced to pass a continuing resolution (CR) to keep the government running on current levels for a few more months. Budget experts and congressional aides expect Congress to follow that same pattern this year, likely punting the debate over 2018 funding into December.

The president knows he'll face an uphill battle for his wall on Capitol Hill. He's been calling for Senate Republicans to get rid of the filibuster, which requires 60 votes to advance most legislation. Any government funding package that includes funding for his planned border wall would almost certainly hit a dead-end in the Senate this fall because Senate Democrats would oppose it, and therefore Republicans would be short of the 60 votes required to proceed.