Washington (CNN) President Donald Trump said he will release the transcript of another phone call with the President of Ukraine "probably" on Tuesday -- this communication having taken place in April before the July conversation at the heart of the impeachment inquiry.

"They want to have a transcript of the other call, the second call, and I'm willing to provide that," the President told reporters Saturday on the tarmac at Joint Base Andrews, before boarding Air Force One.

Trump said he first spoke with Ukrainian President Volodymyr Zelensky in April, but his communication with Zelensky in July has so far been the focus of House Democrats' impeachment inquiry. In September, the White House released a rough transcript of that July 25 call following a whistleblower complaint that alleged Trump solicited "interference" from a foreign country to help his 2020 presidential campaign.

Trump has denied doing anything improper.

On Saturday, the President called the April call transcript "very important."