By Dave Goldiner

New York Daily News

President Donald Trump’s ex-special envoy to Ukraine is set to defy the impeachment-threatened leader by testifying to Congress about the extraordinary effort to dig up dirt on Democratic presidential front runner Joe Biden.

Kurt Volker, who quit under pressure after the intelligence whistleblower filed his explosive report, will become the first official impeachment committee witness Thursday even after Secretary of State Mike Pompeo sought to block past and present diplomats from spilling the beans about the shocking effort to smear Biden.

Volker is not considered a Trump loyalist and reportedly felt he was “forced out” by the president’s loyalists.

He is expected to point out the risks created by the freewheeling effort led by presidential lawyer Rudy Giuliani to unearth damaging information about Biden and his son, Hunter, CNN reported.

Volker delivered dozens of pages of documents to Congress Thursday morning ahead of his planned deposition. It was not immediately clear whether the documents detail Volker’s side of his conflict with Giuliani.

The whistleblower named Volker as someone who sought to “control the damage” from Giuliani efforts, which forced Ukraine’s embattled government to take sides in an American partisan fight or risk losing critically needed defense aid to fight Russian aggression.

“On the side, you had Rudy Giuliani and he’s out there pursuing the personal interests of Donald Trump … and the long-debunked theory about vice president Biden,” Steven Pifer, who served as ambassador to Ukraine under President Barack Obama, said on CNN. “That detracted from Ambassador Volker’s role of pursuing America’s national interest of supporting Ukraine.”

Giuliani has at times claimed that he was acting with the explicit support of American officials.

The ex-mayor flashed his cell phone during a Fox News interview to display what he said were fawning text messages from Volker, who was tasked with arranging meetings between Ukrainian officials and Giuliani.

Volker is a career foreign service professional and leads a foreign policy institute. He was a friend oflate Arizona senator John McCain, who famously feuded with Trump.