WASHINGTON (AFP) - Republican White House hopeful Donald Trump will announce his much anticipated pick for vice-president on Friday (July 15), his campaign chairman told CNN.

Mr Trump will make the announcement from New York, Mr Paul Manafort told the broadcaster on Wednesday evening. This was confirmed by Mr Trump in a tweet later.

Among those believed to be at the top of the real estate billionaire's list of potential running mates are Indiana Governor Mike Pence, New Jersey Governor Chris Christie and former speaker of the House Newt Gingrich.

On Tuesday, Mr Trump campaigned in Indiana for a second straight day with Mr Pence, the 57-year-old governor who is seen as someone with a steady tone who might soften Mr Trump's combativeness.

According to CNN, Mr Trump and three of his children had breakfast with Mr Pence in the governor's mansion on Wednesday. Mr Gingrich also met Mr Trump during the day, while Mr Christie talked with him on the phone.

Mr Christie, a tough-talking politician himself, campaigned with Mr Trump in Virginia on Monday.

Mr Trump has voiced support for Mr Gingrich - who himself ran for president in 2012 - telling the New York Times that "Newt is Newt. He's a good guy."

Mr Trump's vice-presidential pick could be one of the most important decisions he makes on the campaign trail as he seeks to present a competent, steady wingman or woman to US voters after a turbulent primary season during which his provocative rhetoric frustrated many conservatives.

Next week, the Republican Party will head to Cleveland, Ohio, for a national convention at which Mr Trump will be formally nominated to run against his Democratic rival, former secretary of state Hillary Clinton.