Bill Kristol says 'impressive' candidate set to enter race and challenge Donald Trump

Mr Kristol has been the centre of efforts to find someone to take on the Republican nominee

Mr Kristol has been one of Donald Trump's most outspoken critics (ABC News )

A leading conservative has claimed that Donald Trump will be challenged for the presidency by a impressive independent candidate with a “real chance” of beating the Republican nominee.

In a tweet on Sunday evening, Bill Kristol, an outspoken critic of Mr Trump and editor of the Weekly Standard, a respected conservative magazine, declined to give further details.

“Just a heads up over this holiday weekend: There will be an independent candidate—an impressive one, with a strong team and a real chance,” he said.

While Mr Trump has secured the Republican nomination ahead of the party’s July convention - something many believed would be impossible - earlier this month, the Washington Post reported that there was an active effort underway by conservatives to find an alternative candidate.

Among the names mentioned as someone conservatives could gather around were former Oklahoma Senator Tom Coburn, former Secretary of State Condoleezza Rice and retired Army general Stanley McChrystal.

The newspaper said those involved in the effort conceded that an independent campaign at this late stage was probably futile, but were doing so because they were “repulsed” by the prospect of Mr Trump as commander-in-chief. Among those named as being involved in the effort were conservatives such as Mr Kristol and Erick Erickson, and strategists including Mike Murphy, Stuart Stevens and Rick Wilson.

On Sunday night, Mr Trump, fresh from attending a rally in Washington DC to honour military veterans, responded to Mr Kristol with a barrage of comments on social media. He also said - pointing to something that many political commentators believe - that the presence of an independent candidate would greatly increase the Democrats’ likelihood of victory.

Mr Trump called Mr Kristol a “dummy” and “an embarrassed loser,” suggesting the pundit reflects a lack of party unity that could affect the ideological composition of the Supreme Court.

“The Republican Party has to be smart & strong if it wants to win in November. Can’t allow lightweights to set up a spoiler Indie candidate!” Mr Trump said.

Mr Kristol has repeatedly been the centre of rumblings around a possible independent bid. Earlier in May, Mr Kristol met with former Republican presidential nominee Mitt Romney to discuss possible options for independent candidates.