WASHINGTON (Reuters) - U.S. House Intelligence Committee Chairman Adam Schiff says his panel is communicating with an attorney representing the whistleblower who came forward to raise concerns about President Donald Trump’s phone call with Ukraine’s president and that the intelligence staffer would like to testify this week.

The whistleblower’s attorney is talking with the acting Director of National Intelligence about how to proceed, Schiff said in a post on Twitter.

Trump confirmed on Tuesday he had withheld nearly $400 million in U.S. aid to Ukraine but denied accusations he did so to leverage Ukrainian President Volodymyr Zelenskiy to initiate an investigation that would damage Democratic political rival Joe Biden.

Trump also said on Tuesday his administration would release “the complete, fully declassified and unredacted” transcript of his call.