Cher believes Donald Trump does not have the ability to tackle serious world issues Reuters/Fred Prouser

Business mogul Donald Trump has already lost a supporter in his presidential bid, with singer Cher mocking the real estate magnate's hopes to run in the 2016 US election.

The 69-year-old diva has no confidence in Trump's ability to lead America and take over from Barack Obama in the next bout of elections, describing the businessman as "obnoxious".

In a lengthy Twitter rant, the Just Like Jesse James hitmaker told her followers:

Doubting whether Trump, also 69, would be able to tackle serious foreign issues such as the terrorist threats from Islamic State (Isis), Cher added:

The Oscar-winner also believes that the Apprentice boss, who is planning to run for the Republicans, would only care to serve the interests of the privileged, adding:

During Obama's 2008 presidential campaign, Cher publicly affirmed her support for the Democratic Party, telling Matt Lauer on the Today show: "You know [Obama is] by far the best candidate. I don't know I'm an independent but I just don't think I could ever vote for a Republican. I guess maybe it would depend on the person but I just think our views are diametrically opposed."

Trump is yet to respond to Cher's views, although he is perhaps too busy trying to launch his new political career.

Donald Trump
Reality TV star Donald Trump has announced his campaign for the 2016 Republican presidential nomination Reuters/Brendan McDermid

In a press conference announcing his presidential plans for 2016, Trump said: "Sadly the American dream is dead, but if I get elected president I will bring it back. Bigger, better and stronger than ever before.

"Our enemies are getting stronger and stronger by the day, and the US as a country is getting weaker and weaker. How stupid are our leaders, how stupid are our politicians to let this happen? Our president doesn't have a clue."

In a particularly bold promise that most likely prompted Cher's rant, Trump told his audience: "Nobody will be tougher on Isis than Donald Trump."