Trump renews national emergency threat over wall

US President Donald Trump has renewed a threat to declare a national emergency to fund the construction of a wall on the Mexican border.
A row with Democrats over funding the wall has left the government partially shut down for 20 days, leaving some 800,000 federal employees unpaid.
On Saturday, the shutdown becomes the longest in US history.
Mr Trump says the wall, a key campaign pledge, is needed to tackle a security crisis of illegal immigration.
The Democrats say the wall is an “immorality” and a waste of taxpayers’ money.
President Trump has refused to sign legislation to fund and reopen the government if it does not include $5.7bn (£4.5bn) for the wall.