Elizabeth Neumann, who served in the department until April of this year, indicated the rise of white supremacy and the handling of the coronavirus pandemic as her reasons for turning on the president.
In a new attack ad, published by Republic Voters Against Trump on Wednesday, Ms Neumann describes her former role as assistant secretary for counterterrorism, saying she examined emerging threats from domestic terrorists.
“Over the period of 2017 to 2018 we started to see that rise of the white supremacist agenda,” she said, describing the groups as a “growing threat”.
She goes on to attack the president’s actions and language, labelling them racist and accusing them of facilitating the rise of such movements.
“The president’s actions and his language are in fact racist ... those words gave permission to white supremacists to think that what they were doing is permissible,” she says.
Ms Neumann also criticises Mr Trump’s handling of the coronavirus pandemic, claiming that he prevented officials from preparing for the crisis in an attempt to prioritise the economy and his presidential campaign.
“I’m sorry, Mr President, you were hired to handle America’s worst day,” Ms Neumann says. “And you’ve absolutely failed.”
The former official goes on to say that she will be voting for Democratic presidential nominee Joe Biden in November.
“We are less safe today because of his leadership,” she says of Mr Trump. “We will continue to be less safe under his control.”
When contacted by The Independent about the advert, Tim Murtaugh, Trump 2020 communications director said: “Mr Biden has been a failure in the Washington Swamp for a half-century, so no one should be surprised when Swamp creatures gather to protect one of their own.”
“President Trump has unprecedented support — over 95 percent — among real Republican voters and is also making strong inroads in Mr Biden’s core Democrat constituencies, like Black Americans, Latinos, and union members. President Trump’s record of success for all Americans will carry him to victory in November.”
Earlier this month, another former employee of the department, Miles Taylor, also came out against the president in his own scathing attack ad for the Republican group.
“What we saw week in and week out, and for me, after two and a half years in that administration, was terrifying,” Mr Taylor, who had served as Department of Homeland Security chief of staff under former secretary Kirstjen Nielsen, said in the video.
Mr Trump hit back at Mr Taylor in a tweet following the video’s release calling him a “disgruntled employee” and insisting that he had never heard of him, despite photographs of them together in the Oval Office.
“With that said, a former DISGRUNTLED EMPLOYEE named Miles Taylor, who I do not know (never heard of him), said he left & is on the open arms Fake News circuit. Said to be a real ‘stiff’. They will take anyone against us!”, he said.
Both Mr Taylor and Ms Neumann are part of a group of 73 former US national security officials from across four Republican administrations who have banded together against the president in the run-up to the election.
Anthony Scaramucci, who briefly served as White House communications director, has also endorsed the Democratic nominee. Former national security chief John Bolton has said he will not be voting for Mr Trump or Mr Biden.
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