Department of Homeland Security Secretary Kirstjen Nielsen said on "Fox & Friends" that President Trump clearly has the authority to declare a national emergency on border security. 

The Republican-led Senate is expected Thursday to approve a resolution to annul the emergency declaration, which would likely trigger Trump's first veto of his presidency. 

In remarks at the White House Wednesday, Trump said senators can vote how they choose, but cautioned that voting with Democrats would be a "bad vote" for some Republicans. 

"Anybody going against border security, drug trafficking, human trafficking, that's a bad vote," he said. 

Speaking at a Customs & Border Protection training facility in Harpers Ferry, West Virginia, Nielsen told Pete Hegseth that the crisis is not "manufactured," as Democrats have repeatedly claimed.

"Is there an emergency? I could certainly talk to you and anyone who's willing to listen about how that is a definitive and resounding 'yes,'" she explained, blaming Congress for "failing to act" for decades on border security and immigration laws.

She said the men and women of DHS "have sworn an oath to protect communities" and enforce the laws enacted by Congress.

"I really fear for our democracy when the body who creates the laws is telling the body who enforces the law, 'just don't enforce the law.' If they don't like the law, they should change it," she said.

Watch the full interview above, plus check out Pete's sit-down with VP Mike Pence at the same location.

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