Donald Trump is now being advised by 'Fox News' conspiracy theorist Sean Hannity

Mr Hannity is a leading conservative commenator and broadcaster

The Fox News anchor and broadcaster Sean Hannity has never hidden his admiration for Donald Trump.

During one of several fawning interviews during the course of the campaign, Mr Hannity in June made clear that support extended to the ballot box.

“I am not the corrupt press. I’m actually the conservative here,” said Mr Hannity. “Well, I’m an opinion show. And I don’t hold back that I’ll be voting for Donald Trump in November.”

Mr Hannity is a hero for many conservatives (AP)

On Monday, the extent of Mr Hannity’s backing for the Republican candidate became clearer when it was reported that the Fox News broadcaster was acting as an unofficial adviser to Mr Trump’s campaign.

In a development that asked questions about the firewalls journalists typically seek to keep between themselves and the politicians they report on, the New York Times said Mr Hannity had “for months peppered Mr Trump, his family members and advisers with suggestions on strategy and messaging”.

The report said that three sources within the Republican’s campaign had suggested that Mr Hannity was behaving as if he wanted a role in a possible Trump administration.

Asked about his conversations with Mr Trump, Mr Hannity said: “Do I talk to my friend who I’ve known for years and speak my mind? I can’t not speak my mind.”

He said that he said nothing to Mr Trump in private that he did not say in private, and he added: “I never claimed to be a journalist.”

But many believe the development highlights a disturbing trend about the increasing proximity of some journalists and politicians. Professor Todd Shaw, a political scientist at the University of South Carolina, said that broadcasters such as Fox News, and more recently MSNBC, had been acting like echo chambers for certain political constituencies.

“As a result, this is not entirely surprising, but many will see it as a problematic development,” he said.

Mr Hannity, 54, is a well known, influential voice among conservative media in the US. A former talk radio host, he was one of the first people to signed by the Fox News channel when it was established in October 1996. (The channel’s founder, Roger Ailes, who was recently forced to resign amid allegations of sexual harassment, is also serving as an advisor to Mr Trump. Mr Ailes has denied the allegations of sexual harassment.)

For many years, Mr Hannity was one part of the Hannity and Colmes show on Fox, in which a meek fellow anchor, Alan Colmes, sought to put a liberal counter to Mr Hannity’s conservative rhetoric. The show ended in 2009, and was replaced by Hannity, in which the conservative anchor had no foil to offset his right wing opinions.

Mr Hannity has interviewed Mr Trump on many occasions. In recent weeks, his show, which broadcasts at 10pm and is filmed in New York, has carried a series of claims - widely debunked by other broadcasters - that Mr Trump’s rival, Hillary Clinton, is suffering from an undisclosed medical condition.

Over the course of a week, he informed his viewers that a photo “which shows Hillary Clinton apparently needing assistance to climb a flight of stairs at a campaign stop back in February”.

He also assembled a panel of so-called experts to talk about Ms Clinton’s health, despite her doctor releasing a letter last July summarising her medical history and saying she was in “excellent” health.

The broadcasts appeared to be coordinated with Mr Trump, who told supporters she “lacks the mental and physical stamina to take on Isis, and all the many adversaries we face.”

Neither Fox News or the Trump campaign immediately respond to inquiries. Mr Hannity also did not respond to an emailed question.

Jeanne Zaino, Professor of Political Science at Iona College in New York, told The Independent there was undoubtedly no shortage of journalists in history who had advised presidents. Yet, she said as journalism had become more professional over the centuries and decades, there was no evidence in recent history of anything so blatant or “shameless”.

She added: “It raises serious questions about an institution that is considered so important that it is mentioned in the Constitution.”