The Republican Party's leading White House contenders will spar with billionaire Donald Trump on Thursday, as 17 candidates meet for the first debates of the 2016 race.

Six months ahead of the primary to choose the Republican flagbearer, real estate mogul Trump has taken an unexpected lead in the run-up to the encounter in Cleveland, Ohio.

His brash off-the-script style offends some but has distinguished Trump from a packed field of candidates, who have furiously tried to garner the same level of attention.

Thursday's political event is divided into two parts. The main debate with 10 candidates will take place at 9:00 pm (0100 GMT) in the city of Cleveland, Ohio.

A second tier debate for seven candidates lower in the polls will have taken place four hours earlier.

Both debates will be moderated by Fox News, a network influential with American conservatives, in partnership with Facebook.

The gaggle of candidates is hardly a "Who's Who" of well-known political figures of the right.

After Trump and Jeb Bush, son and brother of former presidents, the list's clout drops off considerably.
Wisconsin's Governor Scott Walker and former Arkansas governor turned television host Mike Huckabee are among the few to have drawn much national attention previously.

All eyes will be fixed on front runner Trump, who will take the first question.

He has rarely failed to disappoint in provoking his rivals. In one recent speech Trump blasted one as "weak," another as an "idiot" and third as a "buffoon."

But -- besides his slogan "Make America Great Again" and a few controversial positions on hot-button issues such as immigration -- Trump has yet to set out a detailed platform.

He will be ripe for broadsides from opponents over his lack of political experience -- this from contenders who are almost all seasoned politicians.

Trump's previously liberal-leaning positions on issues such as abortion and guns will also likely draw criticism from traditional conservatives.

"I probably am the target," Trump said on ABC.

"I've evolved like a lot of other people. Ronald Reagan evolved, Ronald Reagan was a Democrat and he became a Republican."
- On the issues -

Immigration is a favorite subject of Trump, who has promised to build a wall between Mexico and the US to stop illegal immigrants.

He sparked a firestorm and offended many Hispanic voters when he said Mexico was not "sending its best" and said the immigrants were bringing drugs and crime to the US.

"He's saying a lot of the things that everybody thinks and he says them without being embarrassed," said Brad Roller, in a bar in Cleveland after a campaign event for Senator Marco Rubio.

"The media has been trying to get him, and it's not working very well because he's connecting directly to people."

While he draws a frenzy of headlines, Democrats say Trump's stated positions are similar to those of the Republican mainstream: no naturalization of illegal immigrants, repeal of the health care reform introduced by President Barack Obama and opposition to abortion.

"The rest of the Republican field will no doubt desperately compete to differentiate from Trump in style, but the truth is, they don't differ on the substance," said Joel Benenson, strategist for Democrat front-runner Hillary Clinton.
Nine debates are scheduled by the Republican party by February. The next will take place September 16.

The candidates in Thursday's main debate are: Trump, Bush, Walker, Huckabee; neurosurgeon Ben Carson; senators Ted Cruz, Marco Rubio and Rand Paul; and governors Chris Christie of New Jersey and John Kasich of Ohio.