The spot will air on national television during the hearing, and on digital platforms before then.
Political independents, a group that Trump won in last year's election, are also largely critical.
Early Wednesday, Trump announced his pick to succeed Comey at the FBI - Chrstopher Wray, a former Justice Department official who served as New Jersey Gov. Chris Christie's lawyer during the George Washington Bridge lane-closing investigation.
Comey is expected to testify before the Senate intelligence committee on Thursday about his encounters with Trump in the weeks before his May 9 firing, and his conversation with Sessions could come up at the hearing.
"If he confirms what's been alleged, it's obviously serious business", Rep. Adam B. Schiff of California, the top Democrat on the House Intelligence Committee, said in an interview. "I think your unwillingness to share that conversation is an issue". There's bipartisan agreement, the email says, that Comey "needs to answer a simple question about his conversations with President Trump: If you were so concerned, why didn't you act on it or notify Congress?"
"I wish him luck", Trump said of Comey during a White House meeting with Republican congressional leaders.
The events involving Coats show the president went further than just asking intelligence officials to deny publicly the existence of any evidence showing collusion during the 2016 election, as The Washington Post reported in May.
In a House hearing last month, Coats and Rogers refused to discuss reports that Trump also had sought to pressure them to ease up on the Russian Federation inquiry.
But Comey insisted on testifying in public, raising the likelihood that he will provide an account of his private meetings and calls with Trump.
The nation's top intelligence official told associates in March that President Donald Trump asked him if he could intervene with then-FBI Director James Comey to get the bureau to back off its focus on former national security adviser Michael Flynn in its Russian Federation probe, according to officials.
"I understand the Special Counsel has not fenced him off in any way, shape or form", Sen.
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The chairman off the Senate intelligence committee, GOP.
Brian Hale, a DNI spokesman, declined to comment on whether Trump asked Coats to intervene with Comey regarding the Flynn investigation. "We have an aggressive investigation going on right now", Rep. K. Michael Conaway, R-Texas, who is leading that inquiry, said Tuesday.
The Senate hearing Thursday is expected to focus, in large part, on those memos.
The person, who was not authorized to discuss the matter by name and spoke on condition of anonymity, told The Associated Press the comment was made because of concerns Comey had about Trump.
Even conservatives are about twice as apt to have low trust in what Trump says about Russian interference than to have substantial trust, 60-33 percent.
The two refused to comply with the request, which they regarded as inappropriate, the Post report said.
When he fired Comey, Trump declared in a statement that Comey had told him three separate times that he was not under FBI investigation.
The White House did not respond to questions of whether Trump would claim executive privilege Wednesday.
After stories described Comey's memos of his conversations with Trump, the president said on Twitter that the ousted Federal Bureau of Investigation director had better hope that no secret "tapes" existed of their discussions, an implied threat that added echoes of Watergate to the drama.
Michael Flynn, Trump's national security adviser, was sacked in February.
Meanwhile, with Comey's highly anticipated congressional testimony just a day away, the White House and its allies are scrambling for ways to offset potential damage.
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