Donald Trump has been unnerved by Kamala Harris’s surge in the polls and is questioning the performance of his campaign team, according to reports in the US.

The former president’s unease comes as the latest opinion poll, conducted by Marquette University Law School, gave Ms Harris a six-point lead among likely voters.

Trump has been upset by his opponent’s poll ratings and the media coverage she has enjoyed, the Washington Post reported.

The former president has been complaining relentlessly and asking friends how they believe his campaign is performing.

There are fears that some events have “gone off the rails”, causing some bickering within the Trump campaign.

Despite weeks of speculation that Joe Biden would step aside, allies fear the Trump campaign was still caught off-guard when Mr Biden was replaced by Ms Harris.

On Thursday, Trump complained that the media was underestimating the size of his crowds compared to those drawn by Ms Harris.

“If Kamala has 1,000 people at a rally, the press goes “crazy,” and talks about how “big” it was - And she pays for her “crowd.” When I have a rally, and 100,000 people show up, the fake news doesn’t talk about it,” he wrote on Truth Social.

Republicans had believed Trump was heading for a landslide victory after the unsuccessful assassination attempt. But the mood has changed with the Harris Walz campaign not only enjoying a poll boost, but also a spike in campaign donations.

Earlier this month, official figures showed that she had raked in $310 million (£242 million) in July – more than double the $138.7m by the Trump campaign.

Speculation that Trump could shake up his campaign team was fuelled by Kellyanne Conway’s visit to Mar-a-Lago, with his former counsellor having masterminded the 2016 triumph.

However, while there is some discomfort, the Washington Post reported that there has been little panic.

“Trump is going to have to win this election a second time,” Richard Porter, a former member of the Republican National Committee, told The Telegraph.

Jeff Lord, who worked in the Reagan White House, said there was no need for the Trump campaign to press the alarm button.

“That kind of thing happens all the time. When you get a new nominee there is a surge in the polls and then you get back to business,” he said.

“There will be more after the democratic convention, once that’s over things will get back to normal.

“The polling is irrelevant; they get a surge in good publicity then it starts to fade away.

“When it settles in and you have the two tickets facing each other, that’s when you have to take notice.”

No more Biden ‘rose petals’

Meanwhile, Nancy Pelosi joined others in trying to persuade Joe Biden to stand down because she feared the president was placing “rose petals” in Trump’s path to victory.

“Now I was really asking for a better campaign. We did not have a campaign that was on the path to victory. Members knew that in their districts,” she told reporters in an interview to promote her new book.

She added that the disastrous presidential debate in late June and its aftermath made a Trump victory inevitable.

“My goal in life was that that man would never set foot in the White House again,” she added, the Washington Post reported.

While ducking the question of whether she directly told Mr Biden to stand down, Ms Pelosi admitted she did speak to many senior Democrats who wanted a change at the top of the ticket.

The former Speaker of the House said she had received hundreds of calls from Democrats worried about the election.

Recalling her appearance on MSNBC on July 10, she said that it had prompted Democrats to believe that Mr Biden was wavering over whether to stay in the race.

It led to more than two dozen Democrats pleading with Mr Biden to stand aside.

“He may think that my statement unleashed something – I don’t know, because I haven’t spoken to him since.”

Ms Pelosi had advised him not to debate Trump, even though she was confident he could handle it.

Interviewed in the New Yorker, Ms Pelosi admitted she was worried about the consequences of her part in persuading Mr Biden – a friend for many years – to step aside.

Asked whether their friendship would remain, she replied “I pray so. I cry so. I lose sleep on it.”