Washington(CNN) Secretary of State Mike Pompeo accused Sen. Robert Menendez and his staff Thursday of "conducting character assassination attempts" -- a charge the New Jersey Democrat dismissed as one of Pompeo's "high level temper tantrums."
In the weeks since State Department inspector general Steve Linick was fired, the fraught relationship between the top US diplomat and the top Democrat on the Senate Foreign Relations Committee has appeared to grow increasingly adversarial. Thursday's letter to Menendez is the latest jab from Pompeo, who finds himself under scrutiny and on the defensive after recommending the removal of his agency's independent watchdog.
On Friday, that scrutiny intensified as Menendez and fellow Democrats House Foreign Affairs Committee Chairman Eliot Engel and House Oversight Committee Chairwoman Carolyn Maloney announced they were expanding their probe into Linick's ouster to include transcribed interviews with officials. A State Department spokesperson said the department "is carefully reviewing various requests for information, records, and interviews with State Department personnel, and is committed to engaging in good faith discussions with the Chairman (Engel) concerning these requests."
A senior State Department official told CNN "it is clear" that Pompeo "feels the pressure" amid the fallout from Linick's firing and the subsequent investigation.
"He wears his feelings on his sleeve. He does not hide his frustration and anger. We see it. He never was very personable, but he is very short now," they said.
In the letter dated Thursday, Pompeo does not reference Linick's firing, but instead says he is writing to relay a months-old response from the Office of Special Counsel that found no evidence that the secretary's frequent trips to Kansas violated the Hatch Act.
Menendez had sought a review of Pompeo's compliance with the Hatch Act, which prohibits federal employees from engaging in political activities, in October 2019. The top US diplomat made multiple visits to his home state amid heavy speculation about a potential Senate bid. Pompeo has said he does not intend to run for the open seat, a fact that is noted in the OSC's letter. The filing deadline in Kansas is Monday.
In his letter, Pompeo wrote that the Office of Special Counsel's finding was "unsurprising" to him, telling Menendez that "the response to your hackery makes clear your continued effort to politicize legitimate and important diplomatic and national security activity was without merit."
Menendez, responding in a statement after receiving the letter, said that "clearly the Secretary of State feels deeply disturbed by the ongoing oversight work of the Senate Foreign Relations Committee."
"However, we will continue to carry out our duties as laid out in the Constitution, including providing advice and consent on nominees, asking tough questions on policy decisions, as well as actions taken at the Department," Menendez said in a statemen. "High level temper tantrums will not stop the Committee from conducting our oversight responsibilities."
Pompeo and Menendez have clashed in the past. Menendez opposed Pompeo's nomination as secretary of state. Pompeo accused Menendez of slow-walking State Department nominees; Menendez countered that they were unvetted and unqualified.
Under the Trump administration, the State Department has been uncooperative with certain Democratic oversight efforts. Most recently, two committee aides told CNN the department, along with the White House and the Department's Office of Inspector General, failed to meet a deadline to turn over documents related to Linick's firing.
At the time of his removal, Linick was investigating whether Pompeo misused a political appointee for personal errands and whether the administration unlawfully circumvented Congress by declaring an emergency in order to sell billions of dollars of weapons, including to Saudi Arabia and United Arab Emirates.
Pompeo has offered limited specific details about his decision to recommend Linick's removal, but has repeatedly said it wasn't retaliatory.
"He was acting in a way that was deeply inconsistent with what the State Department was trying to do. His office was leaking information," Pompeo said in an interview with Fox News Thursday.
An investigation by the Pentagon inspector general found no evidence that Linick or anyone in his office shared information with the media about a probe into the State Department, two sources familiar with the investigation told CNN.
Pressed about Linick's removal during a news conference last week, Pompeo accused Menendez's office of leaking stories to the media in unusually personal terms.
"I don't get my ethics guidance from a man who was criminally prosecuted -- case number 15-155 in New Jersey federal district court -- a man for whom his Senate colleagues, bipartisan, said basically that he was taking bribes. That's a -- that's not someone who I look to for ethics guidance," he said.
The Justice Department dropped the charges against Menendez in January 2018 after he had been acquitted on seven of 18 of them.
The New Jersey Democrat called the broadside "as predictable as it is shameful."
"The Secretary should focus on answering questions and getting his story straight as to why he wanted to target IG Linick," he said.