Washington(CNN) Democrats on the Senate Judiciary Committee are calling on Attorney General William Barr to recuse himself from "matters related to Ukraine" and the Justice Department's investigation into the origins of the Russia election interference investigation.

"He's the attorney general, supposedly of our country, but it becomes clearer every day he's the lawyer for the President," Hawaii Sen. Mazie Hirono, a Democrat on the panel, said Tuesday on CNN's "New Day."

Hirono had previously told Barr to his face that he should resign over his handling of the special counsel Robert Mueller's investigation and report. She had also called on Barr to recuse himself from the Russia investigation.

All 10 Democratic senators who sit on the Judiciary Committee signed a letter last week calling on Barr to step away from the Ukraine investigations and "identify the appropriate official who will be responsible for these matters."

"Impartial enforcement of the law is essential to give the American public confidence in the Justice Department's work," the letter reads. "Your personal connection to these matters creates the appearance of a conflict of interest and gives rise to questions about whether the Department is being used to advance the President's personal interests."

They cite the White House's released transcript of the July 25 phone call between President Donald Trump and Ukraine President Volodymyr Zelensky, during which Trump asked Zelensky to work with his personal lawyer Rudy Giuliani and Barr.

Trump's mention of Barr's name during the call, the senators wrote to the attorney general, "suggests that you may have personal knowledge or involvement in President Trump's requests that Ukraine pursue investigations to serve the President's personal political interests."

The group of lawmakers have also requested that Barr confirm whether he consulted with department ethics officials as to whether he should recuse himself.

Federal prosecutors have been investigating Giuliani's business dealings in Ukraine, and indicted two of Giuliani's associates with campaign-finance related charges earlier this month.

The Justice Department has also been looking into the origins of the 2016 Trump-Russia probe, driven by Barr's suspicions that some of the officials overseeing the counterintelligence probe of the 2016 Trump campaign may have acted improperly.

Barr has sought to establish the independence and credibility of John Durham, a Connecticut-based federal prosecutor leading the criminal investigation.

"He is in charge of the investigation," Barr said of Durham during a Fox News interview. "I'm not doing the investigation."

In an interview with ABC News on Sunday, House Intelligence Chairman Adam Schiff accused Barr of "weaponizing the Justice Department to go after the President's enemies" on Trump's behalf.

Barr disputed that criticism, telling Fox News: "That's completely wrong and there is no basis for it, and I act on behalf of the United States."