Impeachment: Democrats reject witness swap in Trump trial

US Democrats have ruled out a "witness swap" with Republicans in President Donald Trump's impeachment trial.

Lawmakers who are seeking to remove the president from office hope to hear testimony from his former National Security Adviser John Bolton.

But Democrats refused any deal to allow the son of former US Vice-President Joe Biden to be called as a witness.

Mr Trump is accused of abuse of power and obstruction of Congress. He strongly denies any wrongdoing.

House Democrats have up to three days to make their case as they present their arguments in the impeachment trial in the Senate. Mr Trump's defence team will have three days after that for a rebuttal.

Democrats accuse the president of using US military aid as a bargaining chip in an attempt to prod Ukraine into announcing an investigation to discredit his would-be Democratic White House challenger, Mr Biden.

Mr Trump has been touting corruption claims against Mr Biden, whose son Hunter held a lucrative board position with a Ukrainian gas firm while his father was US vice-president and in charge of American-Ukrainian relations.

Attending the World Economic Forum in Davos, Switzerland, on Wednesday, Mr Trump jokingly warned he might confront Democrats by coming to "sit right in the front row and stare at their corrupt faces".

The impeachment trial could end next week, but Mr Trump's fellow Republicans control the chamber and are unlikely to oust him.