Donald Trump threatened in a telephone interview with the CBS network on Tuesday to be 'Mr Veto' and block any Democratic legislation if they win. (EPA Images pic)WASHINGTON: President Donald Trump lashed out at conservative channel Fox News on Tuesday in a sign of early frustration as he watched the US midterm election results at the White House.

The 80-year-old posted three angry messages on his Truth Social network about Fox, blaming its recent ratings decline on not being sufficiently loyal to him.

In one post sent as the first polls closed, Trump said Fox was "way down, not because of me, but because they are AGAINST me!"

In another post Trump blasted one host as "DUMB AS A ROCK", and in a third he slammed a Fox poll of voters' opinions as "always the worst".