Republicans and Democrats on the panel examined and cross-examined the group -- picking over their answers repeatedly. Director of National Intelligence Dan Coats, National Security Agency Director Michael Rogers, Deputy Attorney General Rod Rosenstein and acting FBI Director Andrew McCabe spent much of the hearing explaining the different reasons they wouldn't answer questions.
By the end of the hearing, Senate Intelligence Chairman Richard Burr, R-North Carolina, delivered a clear message to the Trump administration -- they can't avoid answering to Congress forever.
Here are the top five takeaways from Wednesday's hearing.
Wednesday's hearing did nothing to settle questions of Trump's reported attempts to curb the federal Russia probe
and, instead, only increased the intensity of questions.
For a short moment it appeared the hearing may stay focused on foreign surveillance (Coat's 18-minute opening statement on the topic put one audience member to sleep.) But it quickly shifted to an intense examination of the Trump White House's handling of the Russia probe.
"I've never felt pressure to intervene or interfere in any way and shape -- with shaping intelligence in a political way, or in relationship to an ongoing investigation," Coats told Virginia Sen. Mark Warner
, the top Democrat on the panel.
Rogers replied: "I have never been directed to do anything I believe to be illegal, immoral, unethical or inappropriate. And to the best of my recollection, during that same period of service, I do not recall ever feeling pressured to do so."
But Sen. Marco Rubio, a Florida Republican, pressed both of them if Trump had simply "asked" them to rebut Russia stories -- they refused to answer.
2. The White House can block their testimony
As Coats repeatedly said that he would not answer their questions in public, he added that he would answer in a classified session. But, halfway through the hearing, he later offered an important caveat:
"I do have to work through the legal counsel at the White House relative to whether they are going to executive, ah exercise executive," Coats said, before cutting himself off. Rogers followed up, saying, "I likewise respond as the DNI (director of national intelligence) has."
Unlike former FBI Director James Comey, the President could exercise executive privilege over Coats and Rogers because they still work for him.
3. Democrats are angry and attacking, but Republicans are unhappy too
Exasperated Senate Democrats lit into the four intelligence chiefs as they dodged their questions. At one point, Sen. Angus King, a Maine independent who caucuses with the Democrats, blasted Rogers in the middle of his questioning.
"What you feel isn't relevant Admiral," exclaimed King, as Rogers avoided directly answering the questions.
By the end of it, King said they would have to provide a legal answer why they couldn't answer the questions.
At one point, Burr told Sen. Kamala Harris, a California Democrat, to lay off and let the witnesses answer
. But even Burr, who helped advise the Trump transition team, admonished the panel that they can't simply avoid answering at all.
"At no time should you be in a position where you come to Congress without an answer," Burr said.
4. Trump did not find much support in the room Wednesday
The Wednesday hearing was regarding the surveillance program at the center of Trump's claims that he had his "wires tapped"
by former President Barack Obama. And Trump had a handful of sympathetic Republican senators on the panel, including Arkansas Sen. Tom Cotton, who has frequently supported Trump.
But the only senator to ask about "unmasking"
of US names in the surveillance reports -- the core of the Trump counterpunch to the Russia stories -- was Senate Majority Whip John Cornyn of Texas. Cornyn is a strong ally for the White House to have in its corner, but the questions about Russia and Trump's interference washed over the Trump White House narrative.
5. Comey's testimony will only add to questions of how much Trump pressured investigators
Wednesday's hearing was a blockbuster in its own right -- but Comey's written testimony, released Wednesday by the Senate intelligence committee
, shows that Trump was intensely interested in top officials rebutting the Russia stories in public.
Comey states that Trump repeatedly asked him to publicly announce that he was not under investigation for any ties to Russia.
Comey's testimony -- released Wednesday afternoon before senators headed into a classified briefing with Coats -- jibes with reports that Trump wanted Coats and Rogers
to publicly rebut Russia stories.