By leading with a question that required an opinion or a characterization, Warner opened the door for Rogers - a current Trump administration official - to offer one that was helpful to Trump, without requiring him to offer any facts to back it up.
Comey did not say whether he thought the president's actions amounted to obstructing the investigation, a charge made by some Democrats, and which is expected to feature highly in lawmakers' questions Thursday.
In the three plus years that I have been the director of the national security agency to the best of my recollection, I have never been directed to do anything I believed to be illegal, immoral, unethical, or inappropriate.
Both Coats and National Security Agency chief Mike Rogers said they would not discuss any private conversations that they have had with Trump, refusing to answer several questions by Republicans and Democrats as the atmosphere in the hearing room grew increasingly tense.
"Well, I think your unwillingness to answer a very basic question speaks volumes", Heinrich said.
"I am not asking for classified information, I am asking whether or not you have been asked by anyone to influence an ongoing investigation", Republican Senator Marco Rubio said, in a particularly tense exchange. Other reports suggest Trump asked both men to deny the existence of any evidence of coordination between the Trump campaign and Russian Federation.
Director of National Intelligence Dan Coats has declined to answer questions about this publicly.
Comey's statement came hours after two top USA spy agency chiefs skirted questions from the Senate panel about whether the president also "asked" them to intervene in the Flynn probe, while saying they never felt pressured to do so. Mark Warner of Virginia, the ranking Democrat on the committee, lamented that the witnesses could have laid to rest questions about what the president told them about the Russian Federation probe, but they chose not to answer.
"I don't believe it's appropriate for me to address that in a public session, " Coats said. "You swore that oath - to tell us the truth. He is a good guy", Comey quoted Trump as telling him on February 14 as they sat alone together in the Oval Office.
Acting FBI Director Andrew McCabe is also scheduled to testify.
"We have a special counsel who is investigating", Rosenstein said, when asked about a memo he had written that the White House held up as justification for Comey's May 9 firing.
Wednesday's hearing was supposed to focus on the Foreign Intelligence Surveillance Act, the law that governs how USA intelligence agencies conduct electronic surveillance and collect information between foreign powers and "agents of foreign powers" suspected of terrorism. Rosenstein later appointed Mueller to act as special counsel and take over the FBI's probe of Russian interference in last fall's presidential election. Martin Heinrich (D-NM) also did an effective job of pointing out that Director Coats could simply tell the committee that reports of his contacts with Trump were untrue without revealing confidential communications.
Rogers was testifying before the Senate intelligence committee Wednesday about surveillance laws. Mark Warner of Virginia, also lauded the law.