The Speaker of the United States House of Representatives has directed congressional leadersto take steps aimed at removing the president from office.Speaker Nancy Pelosi asked lawmakers chairing House committeesto prepare articles of impeachment against President Donald Trump.The Democratic Party controls the House of Representatives and all of its committees.Impeachment is the process by which the lower house of Congressbrings charges against a U.S. president.The Senate decides if the president remains in officein a trial overseen by the Chief Justice of the Supreme Court.In a recorded statement, Pelosi said that the facts of the case were not disputed.She said, "The president abused his power for his own personal political benefitat the expense of our national security..."Pelosi made the announcement as Democratic lawmakerspush to have an impeachment vote in the House before the Christmas holiday.Only two presidents have been impeached: Andrew Johnson in 1868, and Bill Clinton in 1998.But neither man was forced from office.In 1974, Richard Nixon resigned from the presidency when it appeared he would be impeached.Pelosi's announcement follows a day of hearings in which a group of law professorsmet with the House Committee on the Judiciary.Democratic lawmakers asked three of the four constitutional experts to give evidence.They were Noah Feldman of Harvard University Law School,Pamela Karlan of Stanford University Law Schooland Michael Gerhardt of the North Carolina School of Law.Republican committee members asked Jonathan Turleyof George Washington University Law School.Much of the hearing dealt with what the writers of the 232-year-old U.S. Constitutionwould think about the act of impeaching a president.Feldman said the writers of the Constitution would have considered what Trump did"as exactly the kind of abuse of office, high crimes and misdemeanors, that they were worried about."Congressman Doug Collins, a Republican, answered by saying,"I don't think we have any idea what they would think, with all due respect."The Judiciary Committee is studying whether Trump's actions rateas something punishable by impeachment.The Constitution says the president must be guilty of "high crimes and misdemeanors."Turley told lawmakers that the writers of the Constitutionwanted impeachment to be used rarely.He argued against moving ahead without additional evidence.Democratic lawmakers say Trump abused his powerby withholding about $400 million in military aid from Ukraine last summer.Congress approved the aid earlier this year.The Ukrainians eventually received the assistance.The Democrats say Trump withheld the aid because he wanted Ukrainian officialsto announce an investigation of former Vice President Joe Biden.Biden is seeking the Democratic Party's presidential nomination.White House officials have publicly released records of two telephone callsbetween Trump and Ukraine's president.However, lawmakers dispute the meaning of what was said.Ukrainian President Volodymyr Zelenskiy has said he did not feel pressured by Trump,who says he did nothing wrong.