Columbus Nova, the company linked to the oligarch, paid Cohen's shell company $500,000.
The three senators have 16 questions for Stephenson about who at AT&T set up the contract with Essential Consultants, what its timeframe was, how the payments were structured and who proposed them, and how AT&T determined that Cohen "was qualified to advise on policy matters".
An AT&T spokesman said, "We are aware of the letter and will respond".
Mr. Trump pledged during his campaign to shake up the Washington establishment - to "drain the swamp" - while railing against "the special interests, the lobbyists and the corrupt corporate media that have rigged the system against everyday Americans". More recently, Daniels' lawyer Michael Avenatti alleged that Cohen was "selling access" to president Trump.
Sharif defends 26/11 remark as Pak top brass slams him
A spokesman for Mr Sharif on Sunday said, "At the outset, statement of Nawaz Sharif has been grossly misinterpreted by the Indian media.
"At heart, these companies got exactly what they paid for", Oliver said, "because they wanted to understand how the Trump administration worked and, think about it, they put their trust in a political novice who turned out to be a total moron and who was actually just bilking them for personal gain".
Cohen has been under scrutiny in recent weeks, first over a payment made to adult actress Stephanie Clifford, who goes by the stage name Stormy Daniels, and then for a slew of other payments made to him by large corporations, allegedly for his consultancy expertise. Senators Elizabeth Warren, Ron Wyden and Richard Blumenthal noted that those payments were made, in spite of the fact that Cohen lacks experience and knowledge about tax reform, antitrust issues, and FCC policy.
The payments have come under unusual scrutiny because because they were made into a DE shell company through which Cohen paid hush money to a porn-star who said she had an affair with Trump. I'm closest to the president.
"You want to know how the Trump administration works? Congratulations, you just got a f*****g masterclass".
Oliver called Cohen "a lawyer so shitty he made Trump say 'I need someone good; get me Rudy Giuliani on the phone'".