President Donald Trump speaks while participating in a tour of U.S.-Mexico border wall prototypes near the Otay Mesa Port of Entry in San Diego, California, March 13, 2018. Kevin Lamarque | Reuters

Even as he threatens to shut down the government unless Congress funds his proposed border wall, President Donald Trump revived his claim that Mexico would pay for the barrier. In a tweet Thursday, the president contended that his stance on America's southern neighbor funding the wall "has never changed." He claimed his replacement of the North American Free Trade Agreement would cause Mexico to pay the barrier "just by the money we save." It is unclear how the new trade deal would fund the wall, which carries a price tag of up to $25 billion. Trump tweet With just over a week until funding for parts of the government lapses, Democratic leaders aimed to turn the president's statement against him. Two days after an on-camera spat where Trump said he would be "proud" to shut down the government, Senate Minority Leader Chuck Schumer said he would not approve any additional money for the border wall. "Well, Mr. President, if you say Mexico is going to pay for the wall through NAFTA, which it certainly won't, then I guess we don't have to. Let's fund the government," the New York Democrat said Thursday on the Senate floor.

"Honestly, if the president really believed what he tweeted this morning that his new NAFTA would pay for the wall, he wouldn't be threatening to shut down the government unless American taxpayers fund his wall. You can't have it both ways," Schumer continued. House Minority Leader Nancy Pelosi also questioned what the president meant by his tweet. "The money the businesses make? What money is he talking about that's going to go pay for the wall? It just doesn't measure up," she told reporters Thursday. Pelosi added that "the American people are still paying the price" if benefits from the trade deal went to the wall. WATCH: A history of controversial walls

Trump's tweet Thursday morning further muddles his messaging on the need for congressional funding for his wall. It could give him less leverage as he pushes Democrats to yield and approve money for the barrier. His claim that Mexico will pay for the wall followed comments this week that also raised questions about why he needed taxpayer funding. Trump repeatedly contended the barrier was already being constructed — even though Congress has only approved money to build new or replace existing fencing. The president also suggested the military could construct the wall, though the Pentagon said it has no plans yet to do so. Trump needs nine Senate Democrats to support a funding bill to reach the 60 votes needed to pass one. Schumer has committed to approve $1.6 billion for border fencing and technology, but not the wall as the president has proposed. Trump wants $5 billion in taxpayer money for his wall. Pelosi, who will likely become House speaker next month when Democrats take control of the chamber, has flatly said her caucus will not approve wall funding. House Republicans, who support Trump's push for wall money, can pass a spending bill without Democrats in the current session of Congress.