Trump to Bush: speak English in America

Washington - Republican front runner Donald Trump had a message on Wednesday for his Spanish-speaking rival Jeb Bush as they compete for their party's presidential nomination: lead by "speaking English".

"I like Jeb," Trump said in an interview with conservative website Breitbart News. "He's a nice man. But he should really set the example by speaking English while in the United States."

The jab against Jeb was the latest in a war of words between the two major Republican candidates that has heated up dramatically in recent weeks.

Bush, the son and brother of two presidents, pledged early in the campaign to be the "happy warrior" on the trail.

But he has been upstaged by the brash and bombastic Trump, the billionaire tycoon who shot from nowhere to the front of the pack after announcing his candidacy in June.

Trump belittles Bush

Trump triggered a firestorm by saying Mexico was sending rapists and other criminals illegally into the US.

He has attacked Bush for being a "low-energy" candidate, mocked his rival's immigration plan, and belittled Bush for sliding in the polls while Trump ascends.

Bush lived in Mexico and Venezuela as a young adult, his wife was born in Mexico and he speaks fluent Spanish.

He has broken into his second language on several occasions on the campaign trail, especially when he is in regions with high Hispanic populations like Florida and near the southern US border in Texas.

He has recently begun hitting out at Trump in Spanish and English, in a bid to claw back some support five months before the first-in-the-nation nominating contest in Iowa.

"El hombre no es conservador" - the man is not conservative, Bush told reporters in Miami on Tuesday after a campaign stop, according to the Tampa Bay Times.

"Besides, he tries to personalise everything. If you're not totally in agreement with him you're an idiot, or stupid, or don't have energy, or blah blah blah."

Bush bashed Trump on Tuesday with a new video highlighting the liberal positions Trump has espoused over the years, including The Donald's past support for abortion rights, a single-payer health care system, and for Hillary Clinton, now the Democratic White House front runner.

Trump dismissed Bush's video as "yet another weak hit by a candidate with a failing campaign".