Trump's attacks on Ohr revolve around his personal connection to the so-called Steele dossier that was compiled by former British spy Christopher Steele during the 2016 presidential election. The dossier contains a number of allegations about improper connections between the Trump campaign and the Russian government.
Ohr's wife, Nellie, worked on the dossier when she was a consultant at Fusion GPS, the firm that was commissioned to produce it. Republicans insist that the warrant the FBI obtained to investigate former Trump campaign advisor Carter Page and his ties to Russia is tainted because that dossier was part of the evidence used to obtain it. Trump has said the warrant was used to initiate the investigation that led to Mueller's probe.
"The big story that the Fake News Media refuses to report is lowlife Christopher Steele's many meetings with Deputy A.G. Bruce Ohr and his beautiful wife, Nelly," the president wrote in an Aug. 11 tweet, which is the first to mention Ohr by name.
The attacks on Ohr are part of a broader critique of Mueller's Russia probe which Trump calls a "witch hunt."
The president repeated the attack on Tuesday, writing that "Bruce Ohr of the 'Justice' Department (can you believe he is still there) is accused of helping disgraced Christopher Steele 'find dirt on Trump.'"
Despite Ohr's connections to the Steele dossier, there is no proof that it had any material impact on either the FBI's surveillance warrant for Page or on the Mueller probe.
In July, the FBI released redacted documents that showed that the bureau relied on evidence that was unrelated to the Steele dossier in its application to wiretap Page, and disclosed Steele's political motives.
While the president has alleged that the dossier spurred Mueller's Russia probe, the investigation began after Australian diplomats tipped off U.S. officials following a suspicious encounter with Trump's former foreign policy advisor George Papadopoulos.
The Department of Justice declined to comment.