Hearings on an impeachment trial against President Donald Trump is set to begin in the Senate at 1 pm ET Tuesday. The Senate trial begins a month after the House of Representatives passed two impeachment articles against Trump - for abuse of power and obstruction of Congress - over his alleged efforts to coerce Ukraine into investigating former Vice President Joe Biden as well as his alleged attempts to obstruct the Congressional investigation. The Democrats alleged that in a phone call he made on July 25, Trump requested his Ukrainian counterpart Volodymyr Zelensky to conduct an investigation of his potential presidential rival Joe Biden and his son Hunter Biden in return for releasing U.S. military aid to Ukraine. Trump denied the allegations and describes it as political witch hunt. Trump, who prevented his key aides from testifying before the House, has the option to appear before the Senate himself or depute his lawyers - White House counsel Pat Cipollone and personal lawyer Jay Sekulow - to speak on behalf of him. Supreme Court Chief Justice John Roberts will preside over the trial. Senators will hear from both sides - House prosecutors and White House lawyers - and witnesses if any. After a full day deliberation the Senate will vote on whether to impeach Trump. It requires a two-thirds majority of 67 votes to pass the articles of impeachment in the 100-member Senate, where the Republicans enjoy majority. Unless a mass level cross voting takes place, which is improbable, the impeachment is not going to take place in the Upper House, reports say. The Senate consists of 53 Republicans and 47 Democrats. The trial is likely to last for weeks. Only two U.S. presidents have been formally impeached by Congress — Andrew Johnson and Bill Clinton - but neither of them were removed from office through this political process.