Donald Trump looks all but certain to be acquitted by the Senate as Republicans rejected a Democratic effort to force new evidence and witnesses ahead of the president's impeachment vote.

Just two Republicans broke rank to vote with Democrats in favour of further witnesses, which will likely allow Senate majority leader Mitch McConnell to make good on his previous promise not to act as an impartial juror. In response, Chuck Schumer cast the results as making it impossible for Mr Trump to be truly vindicated.

"If the president is acquitted with no witnesses, no documents, the acquittal will have no value because Americans will know that this trial was not a real trial," Mr Schumer said.

Two potential swing vote Republicans, who Democrats had hoped to break from their party line and ask to hear from witnesses, ultimately decided against the proposition. Senators Lamar Alexander and Lisa Murkowski ultimately rejected the motion.

Following the vote, and his desired outcome, Mr McConnell said that the senators will "confer among ourselves, with the House managers, and with the president's counsel to determine next steps as we prepare to conclude the trial in the coming days".

Before his departure to Mar-a-Lago for the weekend as the Senate debated the next steps in his impeachment trial, the president announced an expansion of his travel ban, adding six additional countries to a list of seven others with travel restrictions under guidance from his Department of Homeland Security. Many of the impacted countries have majority Muslim populations.

The White House also announced the US will deny entry to foreign nationals attempting to enter the US within two weeks of visiting China in the wake of a rapidly developing coronavirus outbreak that has sickened thousands of people in a dozen countries.

The US has declared a national emergency as it responds to 200 quarantined people, including six infected patients, in the US.