Bruce Springsteen has added his name to the list of rockers opposed to Donald Trump, insisting the presidential hopeful is a "moron".

Like many Americans, the Born in the U.S.A. singer was stunned when the property tycoon and reality TV star won the Republican Party's nomination for U.S. leader, despite never holding a political position.

Trump will now face off with Democrat Hillary Clinton in November (16) for the chance to replace Barack Obama in the White House, but his hard-hitting politics and views on immigrants, Muslims and women have turned many voters off - and Bruce is one.

In a new interview with Rolling Stone, Springsteen, who turned 67 on Friday (23Sep16), said, "The republic is under siege by a moron," referring to Trump.

"The whole thing is tragic," he added. "Without overstating it, it’s a tragedy for our democracy... The ideas he’s moving to the mainstream are all very dangerous ideas - white nationalism and the alt-right movement. The outrageous things that he’s done... these are things that are obviously beyond the pale for any previous political candidate."

A fervent Democrat, who was a big supporter of Obama throughout his two terms as president, Springsteen admits he'll be voting for Clinton in November: "I like Hillary," he says. "I think she would be a very, very good president."

And if she needs him on the campaign trail in the weeks ahead, he'll seriously consider being there for her, adding, "I think you have a limited amount of impact as an entertainer, performer or musician. I feel what I’ve done was certainly worth doing and I did it at the time because I felt the country was in crisis, which it certainly is right now.

"I don’t know if we've been approached or not to do anything at the moment. If so, I would take it into consideration and see where it goes."