On the eve of Lt. Col. Alexander Vindman's public testimony before House impeachment investigators, Sen. Ron Johnson (R-Wis.) sent a letter to House Republicans, questioning Vindman's credibility.

Vindman, the National Security Council's top Ukraine expert and a Purple Heart recipient, is set to testify on Tuesday. He listened to President Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky, and immediately shared his concerns over Trump's request that Zelensky launch an investigation into a political rival, former Vice President Joe Biden, and his son, Hunter.

In his letter, Johnson opines that there are "bureaucrats and staff members within the executive branch" who have "never accepted President Trump as legitimate and resent his unorthodox style and his intrusion onto their 'turf.' They react by leaking to the press and participating in the ongoing effort to sabotage his policies and, if possible, remove him from office. It is entirely possible that Vindman fits this profile."

Johnson tried to defend Trump throughout the letter, saying he could not recall Trump ever talking to him about the Bidens, while also attacking the whistleblower whose complaint about Trump's call launched the House impeachment inquiry. "If the whistleblower's intention was to improve and solidify the relationship between the U.S. and Ukraine, he or she failed miserably." Catherine Garcia