'Look forward to a big day!' Donald Trump to visit US-Mexico border
Donald Trump (AFP)

Real estate mogul Donald Trump takes his presidential campaign to the Mexico border Thursday, still riding high in polls despite remarks on immigrants that enraged Latinos and cost him millions in business contracts.

"I am going to the BORDER tomorrow. Will be seeing some really brave people. Look forward to a big day!" he tweeted to his more than 3.3 million followers on Wednesday.

Trump's campaign team said he would tour Laredo, a town on the Texas-Mexico border, visit the border itself, address local law enforcement and deliver a press conference.

The former reality TV star, who has made a fortune in real estate and other business ventures, leads polls among Republican and Republican-leaning independents in his bid to become president.

He has hogged the headlines with a series of outlandish remarks and media stunts, lampooning rivals, insulting career politicians and castigating illegal immigrants.

On Tuesday, he called rival candidate Senator Lindsey Graham "a total lightweight" and in a stunning breach of etiquette read out Graham's cell phone number and urged people to call him.

The same day, he mocked former Texas governor Rick Perry who in recent months has taken to wearing eyeglasses.

"He put on glasses so people think he's smart. People can see through the glasses," Trump said during a speech.

Over the weekend, he provoked a backlash among Republican faithful by trash-talking Vietnam war hero Senator John McCain, one of America's most respected politicians.

McCain, at the time a navy aviator, was held prisoner five years and tortured after being shot down. But Trump was unimpressed.

"He's not a war hero," he said in remarks that were widely condemned.

"He's a war hero because he was captured. I like people that weren't captured, OK?"

Trump has managed to ruffle the feathers of the Republican establishment and has turned almost all of his presidential rivals against him, thanks to incendiary rhetoric.

His presidential competitors, for their part, have ramped up their counter-attacks -- in part to raise their own profiles in a crowded field of Republican presidential aspirants that now numbers 16.

Perry had particularly harsh words for Trump at a press conference on Wednesday.

"Donald Trump's candidacy is a cancer on conservatism, and it must be clearly diagnosed, excised and discarded," the former Texas governor said ahead of the billionaire mogul's visit to his home state, calling Trump's presidential campaign "a barking carnival act."

Trump is also expected to encounter protests when he arrives in Texas, following remarks on the campaign trail that many Hispanics have found deeply insulting.

A fervent critic of illegal immigration, Trump on launching his campaign in New York in mid-June accused Mexican immigrants to the United States as being a source of crime and rape.

"When Mexico sends its people, they're not sending their best," he thundered. "They're bringing drugs. They're bringing crime. They're rapists. And some, I assume, are good people."

Companies such as Macy's, Univision and NBC cut ties with Trump, but the mogul has stuck to his guns, refusing to back down.

The latest opinion poll puts him far into the lead in the race for the 2016 Republican nomination, the favorite at 24 percent.

He outpaced his rivals Scott Walker, at 13 percent, and Jeb Bush at 12 percent, according to the Washington Post-ABC News poll.