New York (CNN) President Donald Trump was incredulous Tuesday as he sat in Trump Tower and watched House Speaker Nancy Pelosi announce she was launching a formal impeachment inquiry against him, sources familiar with the moment say. Sitting in the same building where he launched his long shot presidential campaign four years ago, Trump said he couldn't believe it, he later told people.

He had felt confident after phoning Pelosi earlier that morning. The drive for impeachment in her caucus had ramped up amid reports he pushed the Ukrainian President to investigate Joe Biden , and Trump was hoping to head off a clash. He figured he could de-escalate tensions by speaking with her directly.

It was after that call that Trump made the decision to release an "unredacted" version of the transcript of his July call -- against the advice of aides such as Secretary of State Mike Pompeo, who warned him it would set a risky precedent. Trump wanted to undercut the argument from Democrats that he acted inappropriately, he said, and felt he had nothing to hide.

But when the announcement he would release the transcript did little to quell the growing calls for his impeachment, Trump was in disbelief.

Democrats immediately argued that it wouldn't be enough. They also wanted to see the whistleblower's complaint , which had been found urgent and credible by the inspector general for the intelligence community and was mandated by law to be handed over to the intelligence committees. Administration officials began working out a plan to declassify and redact the complaint so it could be turned over too, all in the hope of easing escalated tensions with lawmakers.

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