Recording appears to contradict president's claims of not knowing the Giuliani associate, a key figure in impeachment proceedings

House Democrats warn skeptical Republican senators at impeachment trial that US president endangering American Democracy, as defense team prepares its case

Senators face long hours listening to arguments in impeachment trial, with key issue of whether to allow additional witnesses still not resolved

Democrats use pulpit to make case against Trump but make little headway in denting procedures seemingly crafted to protect him

Media-friendly attorney says he didn't want to take the case and won't represent the president -- just the constitution -- but he still thinks he can 'kick the winning field goal'

Facing protests from both Democrats and Republicans over a rushed schedule and middle-of-the-night testimony, Mitch McConnell adds more time, allows House documents as evidence

Opening sessions likely to be tangled in procedural motions, with Republicans seeking a speedy process while Democrats want time to field fresh witnesses and documents

As final preparations made for Senate trial, president's legal team claims process is 'dangerous perversion of Constitution,' worthy of condemnation

Ground rules for the trial still unclear; law professor Alan Dershowitz, on president's team, pushing for no new testimony to be admitted; Democrats strongly disagree

The president wants a swift acquittal, which means Republicans will need to override Democrats' demands for witnesses, setting up an intense fight just over the rules