Impeachment proceedings against U.S. President Donald Trump are entering a new phase. 

Chief Justice John Roberts and 100 senators were sworn in to hear the trial that starts next week. 

At the heart of the case Trump's effort to get Ukraine to announce an investigation of a political rival.

Trump lashed out on Twitter saying the impeachment was over a perfect phone call.

That was his conversation with Ukraine's president that sparked the impeachment probe.

CGTN's Owen Fairclough explains the next steps in the trial.