The trial to decide whether to remove U.S. President Donald Trump from office began this week.Trump is charged with abusing his power as president,and with obstructing – or blocking – Congress during its investigation.Lawmakers in the Senate will hear arguments both for and against removal.Seven lawmakers from the House of Representatives are making the argument for removing Trump from office.They are all Democrats; Trump is a Republican.Those Democrats say Trump abused the power of his officeby urging the president of Ukraine to investigate a political rival.During that time, Trump was withholding hundreds of millions of dollars in military aid to Ukraine.The Democrats say Trump was inviting a foreign country to interfere in American politics.And, they say, his request served his own political interestsinstead of the national security interests of the country.Lawyers for Trump will defend the president.They say there is no direct evidence that the presidentwas connecting the release of aid to Ukraine to agreeing to an investigation.They point out that, in time, the aid money was released without any investigation.In addition, Trump's lawyers say it is not unusual for foreign aid to be slowed or stopped.And, they say, presidents have the power to make decisionswithout political opponents questioning their reasons.Democrats from the House of Representatives are also charging Trumpwith blocking Congress's investigation into the president's phone call with Ukraine.They note that one of the jobs of the House of Representativesis to investigate possible wrongdoing by the president.However, they point out that Trump's office directed witnesses not to testifyor give related documents to Congressional investigators.They say that witnesses who chose to come forward suffered public statements from the presidentthat seemed to urge them not to give information.In addition, several government agencies followed the example of the White Houseand refused to provide documents.Trump's lawyers answer that a president refusing to take part in an investigation is not unusual.They say government lawyers and past decisions have foundthat the president is protected from congressional testimony.Their position is that when officials blocked Trump's advisers from speaking or giving information,they were protecting the rights and powers of the president – not blocking an investigation.In addition to the two charges, lawyers from both sides are arguing over a third point:whether a president needs to carry out a crime in order to be removed from office.Democrats say no. They say the U.S. Constitutionpermits a president to be removed for a number of wrong actions.Those include, in the words of the Constitution,"Treason, Bribery, or other high Crimes and Misdemeanors."Trump's lawyers argue that the action must be so badthat it threatens the constitutional order or violates the law.They say nothing that Trump has been accused of meets that level.They warn that if Trump is removed, future presidentsrisk being attacked by opposition lawmakers who guess what they are thinking or feeling.In the end, the senators will decide whether or not to convict the president.A two-thirds vote on either charge is required to remove Trump from office.