Russell Vought, acting White House budget director, said Monday security at the southern U.S. border is "deteriorating by the day," and he's blaming Democrats for refusing to approve President Donald Trump's repeated requests for wall funding.

"This is an area of where we're tired of being right," Vought said on CNBC's "Squawk Box," referring to a government report of a record number of migrant families crossing the U.S.-Mexico border.

The White House is expected to release Trump's budget proposal for fiscal year 2020 on Monday. It is expected to seek $8.6 billion from Congress for additional barriers along the U.S.-Mexico border.

That amount would be on top of the funds Trump will redirect from other programs as part of his national emergency, said Vought, who's minding the Office of Management and Budget after previous OMB head Mick Mulvaney left the agency to become the president's acting chief of staff.

Trump's declaration last month, aimed at circumventing Congress to pay for his wall, is currently being challenged by more than a dozen states. The states said Trump is "trying to rob funds that were allocated by Congress legally to various states."

House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer said they had hoped Trump "learned his lesson" after failing to get his wall funding following the partial government shutdown earlier this year.

"Congress refused to fund his wall and he was forced to admit defeat and reopen the government. The same thing will repeat itself if he tries this again," they said in a joint statement Sunday.

According to the U.S. Customs and Border Protection, more than 76,000 migrants crossed the U.S.-Mexico border last month, more than double the number from the same period last year. The figures help Trump's case for his border emergency, albeit one built around a humanitarian crisis and not security.

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