US lawmakers are preparing to question President Trumps top intelligence official over a whistleblower complaint that sparked an impeachment inquiry. Acting national intelligence director Joseph Maguire initially refused to share the complaint with Congress. It refers to a controversial phone call between Mr Trump and the Ukrainian president, US media report. In the call, Mr Trump pushes Volodymyr Zelensky to investigate corruption claims involving the son of Joe Biden. Mr Biden - the leading Democratic presidential hopeful - says a rough transcript of the conversation released on Wednesday shows the president betrayed his oath of office. Democrats opened an impeachment inquiry against the Republican president on Tuesday, accusing Mr Trump of seeking foreign help in the hope of smearing Mr Biden and of using military aid to Ukraine as a potential bargaining tool. President Trump has dismissed the impeachment proceedings as a hoax and a witch-hunt. The whistleblowers formal complaint was still classified on Wednesday, but some US politicians had been allowed to see it, and senior Democrats called for its immediate release. A House of Representatives vote to impeach the president could trigger a trial in the Senate on whether to remove Mr Trump from office. But Republicans control the upper house so it is considered unlikely that a two-thirds majority to dismiss the president could be reached. Congresss investigation focuses partly on whether Mr Trump abused his presidential powers and sought to help his own re-election by seeking the aid of a foreign government to undermine Mr Biden. Mr Trump denies putting pressure on Mr Zelensky. What did Trump say about Biden in the call? According to notes of the 25 July phone call, President Trump asked his Ukrainian counterpart to look into corruption claims involving the son of Joe Biden, Mr Trumps possible rival in next years presidential election. There is no evidence of any wrongdoing by the Bidens. Mr Trump discusses with newly elected Mr Zelensky the 2016 removal of a prosecutor, Viktor Shokin, according to the notes. He then goes on to discuss Mr Bidens son, Hunter Biden, and the fact that Mr Biden allegedly stopped the prosecution of his son. On the call, the US president also asks Mr Zelensky to work with US Attorney General William Barr and Mr Trumps personal lawyer, Rudolph Giuliani, to look into the matter, according to the notes. The Department of Justice said on Wednesday that Mr Trump had not spoken to the attorney general about having Ukraine investigate Mr Biden, and Mr Barr had not communicated with Ukraine.
