Washington (CNN) The White House released a rough transcript of President Donald Trump's first phone call with his Ukrainian counterpart as Friday's impeachment hearing was getting underway.

The congratulatory conversation contained few of the problematic requests that a later July phone call did. But it did show Trump eager to engage President Volodymyr Zelensky, whom he would later ask to investigate his political rivals.

"When you're settled in and ready, I'd like to invite you to the White House. We'll have a lot of things to talk about, but we're with you all the way," Trump said in the April call.

The release of the transcript came a month-and-a-half after Trump first promised to make it public. He told reporters in September that he was eager to release it, believing it would bolster his claims of innocence as an impeachment inquiry was speeding up.

Indeed, the call contains mostly pleasantries from Trump and Zelensky about the recent Ukrainian election.

"I think you will do a great job. I have many friends in Ukraine who know you and like you," Trump said. "I have many friends from Ukraine and they think -- frankly -- expected you to win. And it's really an amazing thing that you've done."

After Zelensky praises the Ukrainian people, Trump mentions his onetime ownership of the Miss Universe franchise.

"When I owned Miss Universe, they always had great people. Ukraine was always very well represented," Trump said.

And when Zelensky invites Trump to his inauguration, Trump says he'll dispatch someone at "a very, very high level." Vice President Mike Pence was originally tapped to attend, but later was replaced by Energy Secretary Rick Perry at Trump's behest.

There is a notable omission.

Trump never mentions corruption, despite an official White House readout distributed at the time saying Trump expressed a commitment to working together to "root out corruption."

Asked about the discrepancy between the April readout of the call and the transcript released Friday, the White House placed the responsibility on the top Ukraine expert at the National Security Council: Lt. Col. Alex Vindman.

"The President continues to push for transparency in light of these baseless accusations and has taken the unprecedented steps to release the transcripts of both phone calls with President Zelensky so that every American can see he did nothing wrong," deputy press secretary Hogan Gidley said in a statement on Friday.

"It is standard operating procedure for the National Security Council to provide readouts of the President's phone calls with foreign leaders. This one was prepared by the NSC's Ukraine expert."

That expert is Vindman.

A White House source familiar with what occurred essentially said that Vindman had updated the readout but the White House had sent out the earlier version.

According to the source, the national security adviser reviews and approves a draft press release prepared by the Directorate and reviewed by NSC Legal and NSC Press Office, which is based on prepared talking points for the call and done before it happens.

Typically, the country expert will update the press release to reflect the topics that are actually discussed.

"On April 21, 2019, President Trump did not raise the issue of corruption during the call with President-elect Zelensky, despite the NSC's recommendation that he do so and specific talking points included in briefing materials addressing that important topic," the source said.

"Given that the call occurred on Sunday, April 21, 2019, the White House may not have updated the press release to reflect the contents of the call before it was publicly released," the source explained.

And the classification markings reflect a difference in how the April and July calls were handled. The first call was marked "Unclassified" and "for official use only." The second call was classified as "Secret."

After concerns were raised about the July call, White House lawyers ordered the transcript be placed in a highly classified server to avoid leaks.

The April document, which has been circulating in the White House, has been the subject of debate over the last month. Internal disputes, political maneuvering and diplomatic differences complicated its rollout , people familiar with the matter said.

Trump first raised the prospect of releasing the log of an April phone call with Zelensky on September 25, insisting it would help reenforce his innocence in the then-nascent impeachment crisis. He said at the time that Pence's phone conversations should also be made public.

Ever since, White House advisers have debated the wisdom of releasing additional conversations with Zelensky after a transcript of Trump's July phone call failed to quiet allegations he was pressuring Ukraine to investigate his political rivals.

Trump said last weekend he would probably release the transcript on Tuesday. Tuesday came and went, and he announced on Wednesday the transcript would be released Thursday.

On Thursday morning, a White House official said timing of the release was "up in the air."

Even though the additional phone calls are not seen as troubling inside the White House, some officials view releasing any additional information as risky. They believe Democrats will find a way to weaponize the transcripts, and are wary of providing any more fuel to the impeachment fire. And even some officials not aligned with Trump see a dangerous precedent in releasing transcripts of a president's conversations with foreign leaders.