His tweet followed media reports that his transition team and Republican leaders in Congress are considering a plan to fund the wall through the appropriations funding process as early as April.
“The dishonest media does not report that any money spent on building the Great Wall (for sake of speed), will be paid back by Mexico later!” Trump tweeted.
Mexican President Enrique Pena Nieto’s spokesman, Eduardo Sanchez, declined to comment on the new tweet.
Having the United States fund the construction would break a major campaign promise to force Mexico to pay for the wall, although Trump has also previously suggested Mexico could reimburse the United States later.
Republicans in Congress say they could rely on a law former president George W. Bush signed in 2006 authorizing the building of a “physical barrier” on the Mexico border, Politico reported.
Never fully implemented, the law remains open-ended, meaning a Trump administration could also use it.
Because the measure lacks funding, however, Republicans are considering including it in a spending bill that must be enacted by the end of April to keep the government open, CNN reported.
Raising the stakes in that way would complicate Democrats’ efforts to obstruct the funding, including by use of a filibuster.
But the move paves the way for a potentially bitter showdown if Democratic lawmakers adopt tactics previously used by Republicans who forced government shutdowns under President Barack Obama and former president Bill Clinton.
“Democrats may well find themselves in the position to shut down all of government to stop the buildout of a wall, or of a barrier, or of a fence,” Indiana Republican Representative Luke Messer told CNN on Thursday.
Still, Republicans are reported to believe they could win a battle over one of Trump’s most popular campaign pledges, especially because a number of prominent Democrats voted for the 2006 law, including Obama when he was a senator, Chuck Schumer — now Senate minority leader — and former Democratic presidential nominee Hillary Clinton.
Estimates for the cost of construction range from several billion dollars up to $25 billion, not including other expenses such as maintenance, additional border guards and the buying of private land that would be needed for the wall.
To obtain money for building the wall, Trump can reallocate current fiscal year funding at the Department of Homeland Security. And if he wanted to raise visa and border crossing costs, the relevant US agencies would have to publish regulations to this effect. But these latter steps would still not be enough, said Stephen Yale-Loehr, a professor of immigration law at Cornell University.
“So he would need Congress to pass a funding bill to pay for the wall,” he told AFP.
No plan has yet been agreed, however.
“We’re in talks with him on the details of it as they’re still putting together their team,” Steve Scalise, the number-three Republican in the House leadership, told CNN. “We want President Trump to have all the tools he needs to build the wall.”