TEMPO.CO, Laconia, US - U.S. Republican presidential candidate Jeb Bush on Thursday rejected what he called a bizarre notion voiced by front-running rival Donald Trump that people should speak English in the United States.

Bush, who is bilingual in Spanish and frequently breaks into the language at his events, vowed to keep speaking Spanish whenever he feels like it.

Trump, who has made opposition to illegal immigration a hallmark of his campaign in the November 2016 election, told a news conference in New York that, "We're a nation that speaks English."

"Whether we like it or not, that's how people assimilate," he said, a day after he criticized Bush's use of Spanish.

Bush said Trump's belief that people should speak English in the United States can be taken in a number of uncomfortable ways.

"Taking this to the logical conclusion, I guess, no more French classes for public schools? 'German, no we can't have that. You can only speak English,'" Bush said. "I mean English is the language of our country and people that come to this country need to learn English. That doesn't mean they should stop speaking their native tongue."

Bush said Trump's jibe at him that he "spoke Mexican" while on a visit to the U.S. border was deeply divisive.

"I think this is pretty bizarre to be honest with you. And it sends a pretty ugly signal to people that somehow we're creating a different standard for one group against the other," Bush said.

The deepening feud between Bush and Trump has dominated the Republican race for the 2016 presidential nomination this week with Bush fighting back after Trump called him a "low-energy" candidate.

When Trump personally criticizes him or his family, Bush told his audience in Laconia, New Hampshire, "You're damn right I'm going to fight back."

Talking to reporters, Bush also sharply criticized Trump for an interview the New York billionaire gave to conservative talk show host Hugh Hewitt in which Trump seemed baffled by the names of some major global players and unable to distinguish Hamas from Hezbollah.

Hamas is a Palestinian militant group and Hezbollah is an Iran-backed militant group in Lebanon.

"He ought to know who the players are," said Bush.

REUTERS