Rep. David Cicilline (D-RI) told Fox News Sunday that Special Counsel Robert Mueller is "tentatively" expected to testify in front of the House Judiciary Committee on May 15 - a reversal from Mueller's earlier pledge to remain mum on the contents of his final report, issued last month.
Democrats are seeking more information about Mueller's report on his Russian Federation investigation.
Mr Cicilline later stepped back from that, tweeting that "nothing has been agreed to yet".
The president tweeted after a Democrat on the committee said he was hopeful Mueller would testify, noting that May 15 has been proposed.
An appearance by Mueller, 74, whose public utterances during the two-year investigation consisted of court filings, would promise to be a dramatic day in the nation's capital, with Democrats pushing him to expand on his inability to exonerate Trump on obstruction of justice and his differences with Attorney General William Barr over the presentation of his findings.
Spokespeople for the Justice Department and Mueller declined to comment on Cicilline's remarks, and Mueller's spokesman declined to comment on Trump's tweet.
Senate Democratic Leader Chuck Schumer responded to Trump by saying in a tweet of his own that the president first refused to be interviewed by the special counsel and "now he's trying to silence" Mueller.
Trump also insisted that Mueller's 448-page report found "no collusion" and "no obstruction", overstating the conclusions of the almost two-year investigation.
The attorney general dismissed the letter as "a little bit snitty".
US President Donald Trump talks to reporters during a meeting with Slovakia's Prime Minister Peter Pellegrini in the Oval Office at the White House in Washington, US, May 3, 2019.
Democratic lawmakers expressed their displeasure with Trump's position. He chose instead to release the full redacted report almost a month later.
Cicilline said there has not been "compliance yet" from the attorney general.
Collins pointed out Barr has already testified before the Senate Judiciary Committee.
"Barr's testimony alone - created to protect Trump - isn't going to cut it".
In late March, Mueller wrote a letter to Barr voicing dissatisfaction that a four-page memo to Congress describing the principal conclusions of his investigation into the president "did not fully capture the context, nature, and substance" of his work. "They will testify. The American people deserve the truth".
"Today, Trump announced he is opposed to Mueller testifying before Congress".