The impeachment trial of United States President Donald Trump enters a new phase on Wednesday as senators get their first opportunity to pose questions to House managers and the president's defence team.Entering its ninth day, the impeachment trial will gather speed on Wednesday towards crucial votes in the 100-seat US Senate on whether to call witnesses or acquit and remove Trump. More:What happens next in the Trump impeachment trial?Trump impeachment trial: Defence team ends opening argumentsOpinion: The outcome of the impeachment process is no longer certainSenators will have eight hours on Wednesday and eight hours on Thursday to pose written questions to both sides. Votes are likely to come on Friday."The main thing is to keep questions focused on the major issues of the trial, and that is a range of questions under 'abuse of power' for example," Democratic Senator Bob Casey told Al Jazeera.Until now, senators have been compelled to sit in their seats without speaking as House Democrats and Trump's defence presented opposing views of two articles of impeachment, one for abuse of power and a second for obstruction of Congress. They will still be required to sit silently, but will now have a chance to actively participate in the trial. Republicans and Democrats said they were consulting among themselves on Tuesday night about strategy for the question and answer sessions.With much at stake, Republicans are likely to address their questions to the president's defence team in order to maximise their opportunities to be heard, a Republican staff aide told Al Jazeera.Former US Department of Justice prosecutor Gene Rossi, who has been following the impeachment trial, suggested the following five questions are likely:To House managers: What evidence have you presented that satisfies the statutory terms for bribery and/or extortion or any other federal crime? Is the Government Accountability Office's finding of a violation of the civil Impoundment Act evidence relevant to satisfying the statutory requirements for bribery and extortion?Republicans have argued President Trump was denied due process, access to proceedings and the ability to defend himself in the House impeachment process. Tell the members of the jury specifically how the House failed to provide due process to the president of the United States? Alternatively, for Democrats, explain how the president was given fair process in the House?When did Congress approve the $391m in security aid to Ukraine and when should the money have been released in a perfect world? And by that delay, how many, if any casualties did Ukraine suffer arguably because of the delay?For House managers: Why did you not call John Bolton and Mick Mulvaney as witnesses? Why did you go to court and ask for subpoenas and then fail to fulfil them? Why did you not go the extra mile before you brought this to the Senate? Why did you not exhaust your congressional remedies before using the nuclear bomb of impeachment?For both sides: Most US constitutional scholars reject Alan Dershowitz's legal argument that if you do not have a crime, you do not have impeachment. Is Dershowitz right or wrong and why?Democratic Senator Kirsten Gillibrand said she was considering several questions at this point."I want to hone in on issues that weren't well elaborated by both sides and we will work together as a caucus to make sure we cover all the issues," Gillibrand told reporters.Every senator is expected to have an opportunity to offer at least one question. Senators will rise and be recognised by Chief Justice John Roberts. They will send their questions to the desk to be read out loud and addressed to one side or the other.According to CNN, senators first sent their questions by email to party leaders so they could be organised and duplicates could be sorted."We don't want the same question 10 times," Schumer was quoted by US media as saying. "I am sure that a good number of the questions will give the House managers time to rebut all the holes in the president's lawyers' arguments, which they didn't have in the course of the trial."The questions will then be written on a form that asks for the senator's name, whom the question is for, the question and the senator's signatures. Groups of senators can also submit questions. During the impeachment trial of former President Bill Clinton, one bipartisan question was asked.Republicans and Democrats will alternate and both parties will determine, at least initially, what order senators are recognised.In keeping with past precedent, Chief Justice Roberts on Tuesday urged senators to keep questions succinct and instructed House managers and Trump's defence to limit answers to five minutes, an admonition that drew light laughter from senators. With additional reporting by Tom Szypulski.