The impeachment trial of US President Donald Trump has kicked off with fierce debate from both side as to how it should proceed. In the first vote of the trial, Republicans rejected a bid by the democrats to force the White House to produce more documents and evidence. President Trump is accused of withholding military aid from Ukraine in exchange for political gain. Trump's supporters are demanding a short trial without witnesses. His opponents say that would amount to a cover up. Our North America Correspondent Jon Brain has the story from the US Capitol.