Senators sworn in for Trump impeachment trial

The chief justice of the United States was sworn in Thursday to preside over President Donald Trump's impeachment trial, then immediately swore in the entire Senate body in turn with an oath to ensure "impartial justice" as jurors for only the third such proceeding in American history.

Chief Justice John Roberts made the short trip across the street from the Supreme Court before being ushered to the Senate chamber. The Constitution mandates the chief justice serve as the presiding officer. Roberts, who has long insisted judges are not politicians, is expected to serve as a referee for the proceedings rather than an active participant.

Senators will ultimately render the verdict. The Senate opened the impeachment trial at the start of the election year as Trump seeks another term. Several senators are running for the Democratic Party's nomination to challenge Trump in November.