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The details of how a wall on the U.S.-Mexican border will be paid for have yet to be worked out, despite the president signing an executive order authorizing it, White House Press Secretary Sean Spicer said Wednesday.

Spicer also announced new measures to remove federal funding from sanctuary cities unless related to law enforcement.

“The president is working with Congress and other folks to figure out opportunities for that to happen. There are a lot of funding opportunities that could be used,” Spicer said at the White House daily briefing.

Trump signed an executive order on Wednesday authorizing the start of planning for the wall.

In an interview with ABC News on Wednesday, President Donald Trump again reiterated that Mexico would pay for one of his marquee campaign promises, despite objections from leaders there.

In the interview Trump said negotiations with Mexico about the wall will begin soon and the U.S. will “absolutely” be reimbursed for its construction. Taxpayers, however, will need to front the initial costs.

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“One way or another, as the president has said before, Mexico will pay for it,” Spicer said during a wide ranging press briefing which focused heavily on immigration.

Defund Sanctuary Cities

Spicer also announced the new administration will sign orders aimed at ending so-called sanctuary cities, which don’t arrest or detain those in the country illegally.

“The American people are no longer going to be forced to subsidize this disregard for our laws,” Spicer said.

He said the Department of Homeland Security will prioritize prosecutions and deportations of those in the country illegally.

“Federally agencies are going to unapologetically enforce the laws. No ifs, ands or buts,” he said.

The Democratic leader of California’s State Senate, Kevin de Leon, had a ready response to the plan.

Cutting off funds for cities that refuse destructive deportation programs is unconstitutional. See you in court. https://t.co/NjGfZfvMrd — Kevin de Leόn (@kdeleon) January 25, 2017

Draft Interrogation Order ‘Not a White House Document’

Spicer said he has no knowledge of where a draft executive order asking for a review of the country’s interrogation practices came from.

The press secretary said it is “not a White House document” and the president had not seen it.

The draft order calls for a complete review of how the nation handles terrorist interrogations, leading some lawmakers to worry the administration may reinstate such controversial techniques as waterboarding. The draft document also indicates the new administration may try to reinstate CIA “black sites” used to imprison suspects overseas and use harsh interrogation techniques.

He declined to comment on whether the president was considering the changes.

Voter Fraud Investigation Meant to Understand ‘Where the problem exists’

Spicer said Trump’s announced investigation into voter fraud is meant to “understand where the problem exists, how deep it goes" and called casting ballots “sacred.”

Trump tweeted he will ask for a “major investigation” into voter fraud after claiming to lawmakers at the White House Monday that 3 to 5 million people voted illegally. Spicer said the president believes those numbers based on studies, though the authors of the reports say the conclusions do not support theories of widespread voter fraud and there is no other proof of massive voting problems.

Spicer maintained such voter fraud was likely to have occurred in bigger states where Trump did not compete, like California and New York.

Trump easily won the electoral vote in last year’s presidential contest, but rival Hillary Clinton earned nearly three million more popular votes.