Arnold Schwarzenegger has offered to ''take over'' as US president.

The 'Terminator' actor has hit out at commander-in-chief Donald Trump after the former 'Celebrity Apprentice' star mocked the show's decline in ratings since he departed and the former Governor of California took over at the head of the boardroom.

Trump urged people to ''pray for Arnold'' and branded the new series of 'Celebrity Apprentice' a ''disaster'' during the National Prayer Breakfast in Washington, DC, on Thursday (02.02.17).

He said: ''We had tremendous success on 'The Apprentice', and when I ran for president, I had to leave the show... and they hired a big, big movie star, Arnold Schwarzenegger, to take my place, and we know how that turned out.

''The ratings went right down the tubes. It's been a total disaster, and [executive producer] Mark [Burnett] will never, ever bet against Trump again. And I want to just pray for Arnold, if we can, for those ratings, OK?''

In response, the 69-year-old actor quickly shared a video online and suggested he and the president ''switch jobs''.

He said: ''Hey Donald, I have a great idea: Why don't we switch jobs? You take over TV because you're such an expert at ratings, and I take over your job, and then people can finally sleep comfortably again.''

Arnold - who was Governor of California for eight years until 2011 - previously admitted he would have campaigned to be the Republican candidate for presidency this year if he'd been eligible to run for the position.

The Austrian actor said: ''If I'd been born in America, I would've run.

''Because now? This was a very good time to get in the race.''