never happened before. >> reporter: the bar is high, only two president have been impeached, andrew johnson and bill clinton, both were acquitted but when it comes to donald trump talk of impeachment has been swirling around him ever since he was sworn in, maybe before. just this week the president said it would be bad for the country. >> i don't know how you can impeach somebody who has done a great job. if i ever got impeached i think the market would crash. >> reporter: first, impeachment charges are introduced in the house based on treason, bribery or other high crimes and misdemeanors, the house committee investigates whether the charges are warranted and if yes, lay out the accusations. a simple majority is needed to improve the articles of impeachment and advance the case to the senate. the senate and conduct a trial presided over by the chief