CNN's Anderson Cooper says President Donald Trump may not have learned the lesson Republican senators think he did after impeachment, as his attorney Rudy Giuliani continues to go after the Bidens in Ukraine.

Sen. Joe Manchin (D-WV) defends his guilty votes in President Trump's impeachment trial after Trump insulted the senator on Twitter.

CNN's John Avlon discusses President Donald Trump's firing of impeachment witnesses Lt. Col. Alexander Vindman and US Ambassador to the European Union Gordon Sondland, and the President's ability to stay on message.

The impeachment trial of President Donald Trump had to make it to the Oscars stage.

It seemed perfect. Everything was going Donald Trump's way. Republican senators had refused to allow witnesses in his impeachment trial. They were expected to form a solid red line of defense. And the administration was even hoping some vulnerable Democrats might buck their party and vote to acquit the President.

CNN's SE Cupp says Americans deserve better from their government following political chaos surrounding delayed Iowa Caucus results and the end of President Donald Trump's impeachment trial.

Lt. Col. Alexander Vindman was right when he spoke to his father —who had emigrated from then-Soviet Ukraine to the United States — in those gripping opening remarks to his testimony before the House Intelligence Committee's impeachment hearings last November:

On the evening of President Donald Trump's Friday night massacre -- his vengeful firing of two officials who testified in the impeachment hearings -- anxious Democrats watched seven presidential candidates take the stage in New Hampshire, each eager to persuade voters that he or she is the best positioned to take on the President and prevent him from winning reelection in November.

Lt. Col. Alexander Vindman, the Soviet-born emigre who testified about his President and told impeachment investigators he wasn't afraid to stand up to authority because he was in the US, not under an authoritarian regime, has been let go from the White House. So has his twin brother, Lt. Col. Yevgeny Vindman, a lawyer for the National Security Council. Another key impeachment witness, US Ambassador to the European Union Gordon Sondland, also has been ousted.

Vice President Joe Biden asked the audience of ABC's Democratic presidential debate to stand for Lt. Col. Alexander Vindman, a key impeachment witness President Trump fired hours before the debate.