The historic impeachment trial of US President Donald Trump opened with fireworks Tuesday as Democrats angrily accused Senate Republicans of seeking a "cover-up" without witnesses or new evidence. With the US leader facing potential removal from office for abuse of power, his close ally Mitch McConnell laid out ground rules that would block subpoenaing key witnesses or documents while each side makes its case -- potentially crippling prosecutors' arguments. Flexing his solid 53-47 majority, the Republican Senate leader also made clear he would summarily block any Democratic attempts to change his rules.
