(CNN) - Donald Trump Jr. is returning to the Senate Intelligence Committee to be interviewed behind closed doors on Wednesday, according to a source familiar with the matter.
The appearance of the President's eldest son Wednesday comes after a lengthy and contentious fight that spilled into public view after the committee issued a subpoena to Trump Jr. and he initially balked at testifying for a second time.
Trump Jr.'s allies mounted an aggressive campaign targeting Senate Intelligence Chairman Richard Burr for the subpoena, accusing the North Carolina Republican of helping the Democrats by continuing his committee's investigation even after special counsel Robert Mueller had wrapped up his probe. Many of those criticizing Burr included his own Senate Republican colleagues.
But Burr did not back down from the subpoena, and the committee and Trump Jr. struck a deal for him to testify for two-to-four hours on roughly a half dozen topics, including the key questions the committee has for the President's eldest son about the June 2016 Trump Tower meeting and the Trump Tower Moscow project.
While the committee struck an agreement with Trump Jr. for his appearance, the committee's subpoena is still in effect and he's still coming before the committee under subpoena, according to a source familiar with the matter.
Burr declined to comment Tuesday about Trump Jr.'s appearance to CNN.
The Senate Intelligence Committee is now two years into its investigation into Russian election meddling in 2016. Burr has said the committee is nearly done with its bipartisan probe, but still has a handful of witnesses it needs to hear from. Trump Jr. initially testified before the panel in 2017, but the committee has brought back several witnesses for follow-up questions, including President Donald Trump's son-in-law Jared Kushner and his former lawyer Michael Cohen.
The committee began engaging Trump Jr. to return to the committee in December, and he initially agreed to testify voluntarily twice before postponing, leading to the panel's subpoena issued in April.
Burr has been praised by his Democratic colleagues for keeping the investigation on a bipartisan track while other congressional probes were plagued by partisan fighting. And he was praised the President for stating his committee had not found any evidence of collusion. But Trump questioned Burr's move to subpoena his son after news of it broke last month, calling it "very unfair" and retweeting on Twitter articles attacking Burr.
The committee is interested in hearing again from Trump Jr. because of discrepancies between his testimony in 2017 and what other witnesses have told both the committee and the special counsel's office.
Trump Jr. appeared before the Senate Intelligence, Senate Judiciary and House Intelligence Committees in 2017, and the release of the Mueller report prompted a new round questions about what Trump Jr. told the Senate Judiciary panel, which released a transcript of his interview.
Trump Jr. testified he only told Kushner and campaign chairman Paul Manafort ahead of time about the Trump Tower meeting in which a Russian attorney promised dirt on Hillary Clinton. But then-campaign deputy Rick Gates, who pleaded guilty in the special counsel probe, told Mueller that Trump Jr. talked about a lead on negative information about the Clinton Foundation at a campaign meeting in the days before the Trump Tower meeting.
Trump Jr.'s testimony on the Trump Tower Moscow project has also been scrutinized, in which he said he was "peripherally aware" of the project. But Mueller's report says Cohen testified he discussed the project on multiple occasions with Trump Jr. and that the discussions were not just "idle chit chat."
This story has been updated with additional developments Tuesday.