The Senate impeachment trial of US President Donald Trump resumes Tuesday (Jan. 21) with Democrats calling for his removal from office and Republicans determined to acquit him.
The 100 members of the Senate will gather at 1 PM (1800 GMT) with chief justice John Roberts presiding over the trial.
Trump has been accused of inviting a foreign government to interfere in his re-election campaign by asking Ukraine's president Volodymyr Zelenskiy to investigate his Democratic rival Joe Biden.
Trump is also accused of obstructing the congressional investigation into the matter
The US president denies any wrongdoing and his lawyers will offer a defence.
It will be only the third time a president has endured an impeachment trial, after Andrew Johnson in 1868 and Bill Clinton in 1999.
The 110-page filing from the White House condemned the "rigged" impeachment process, calling the majority vote to impeach there a "brazenly political act ... that must be rejected." Additionally, the White House released Justice Department legal opinions meant to bolster its case that defying subpoenas from Congress did not amount to "obstruction of Congress."
51 is the number of votes needed to pass any motions within the Senate trial.
67 is the number of senators who will need to vote to convict the President to remove him from office
20 is the number of Republicans who would need to vote in favour of a conviction to remove the President from office, assuming that every Democrat and independent votes as expected (There are currently 53 Republicans, 45 Democrats and 2 independents in the Senate).
Trump, will be abroad as his trial opens; he left late Monday for the economic forum in Davos, Switzerland.
In a show of confidence, Trump tweeted a video late Monday touting his achievements in office, including the nation's historically low unemployment rate, booming stock market and rising wages, with the note: "THE BEST IS YET TO COME!"
With reporting by news agencies