Washington D.C. [U.S.A.], June 11 (ANI): Sen. Dianne Feinstein has called on the head of the Senate Judiciary Committee to investigate the issues related to obstruction of justice in the firing of FBI Director James Comey and the probe into Russian meddling in the 2016 Presidential election, using "subpoena authority if necessary."

"It is my strong recommendation that the Judiciary Committee investigate all issues that raise a question of obstruction of justice," the California Democrat wrote in a letter to Senate Judiciary Chairman Chuck Grassley, reported CNN.

"These issues should be developed by our legal staff, presented to us, and be subject to full committee hearings," she wrote in the letter.

In the letter, Feinstein told Grassley she is very much concerned about the Director of National Intelligence Dan Coats' and National Security Agency Director Admiral Rogers' refusals to answer questions from senators.

She even added that she wants to determine whether U.S. President Donald Trump asked Coats or Rogers to take any action on the Russia investigation.

"As I have mentioned to you directly, I am supportive of issuing subpoenas in those cases where we do not receive cooperation," she wrote.

This letter came a day after former FBI Director James Comey testified before the intelligence committee about his conversations with Trump.

Earlier, Trump has said he was willing to testify under oath about his conversations with former FBI director James Comey.

"One hundred percent," Trump said when asked about his willingness to deliver sworn testimony, CNN reported Trump, as saying during a Rose Garden news conference.

Trump denied that he had asked Comey for his loyalty, though, adding, "There would be nothing wrong if I did say it."

The President also denied Comey's claims that he asked him to end the FBI's investigation into national security advisor Michael Flynn.

Trump also twice declined to confirm the existence of White House recordings of the conversations.

"I'll tell you about that sometime in the very near future," Trump said.

Trump said his team emerged "very happy" after Comey's testimony, while also offering a blunt assessment of Comey's testimony before the Senate intelligence panel.

On Thursday, Comey had accused Trump of firing him to try to undermine the FBI's investigation of possible collusion between the Trump Campaign and Russia in alleged efforts to influence last year's presidential election.

Comey told the U.S. Senate Intelligence Committee that the Trump administration had lied and defamed him and the FBI after the President dismissed him on May 9.

The more than two hour-long testimony saw Comey further informing that Trump had directed him to drop an FBI probe against former national security adviser Michael Flynn.

Comey said it should be special counsel Robert Mueller's task to determine whether Trump had obstructed justice, and therefore, had opened himself up to possible impeachment proceedings, keeping the allegations on Russia in mind.

He, however, said that whatever Trump did was "a very disturbing thing, very concerning."

Comey painted a picture of an overbearing president he did not trust and who pressured him to stop the FBI probe of Flynn.

Russia has denied interferin in last year's presidential elections, as has the White House. (ANI)