Republican Donald Trump has taken steps to steer his White House campaign back into favour with his party establishment by endorsing US House of Representatives Speaker Paul Ryan and two Republican senators seeking re-election.

Trump had expressed coolness toward the pair earlier this week.

“I need a Republican Senate and a House to accomplish all of the changes that we have to make,” Trump said during a rally in Green Bay, in northern Wisconsin, Ryan’s home state, on Friday.

“All my life I’ve been told, ‘You have the greatest temperament’,”

He also endorsed Senators John McCain of Arizona and Kelly Ayotte of New Hampshire, whom he called a “rising star”.

“We will have disagreements, but we will disagree as friends,” Trump said.

Ryan, the top US elected Republican, had no plans to attend the event, in a sign of lingering friction between the pair. His Republican primary challenger, businessman Paul Nehlen, did attend, according to a spokesman.

Paul Ryan is the top US elected Republican. Photo: AAP

Trump this week refused to endorse Ryan when he told The Washington Post he was “not quite there yet” – using the same phrase Ryan had used about Trump before finally endorsing him. He said in the same interview that McCain had not done enough for veterans and criticised Ayotte for distancing herself from him during the campaign.

Ryan a rival and potential candidate

Ryan, who was earlier endorsed by Trump’s vice-presidential running mate, Mike Pence, is viewed by establishment Republicans as a possible presidential candidate in the future. He is expected to win a challenge for his House seat in next week’s Republican primary.

Trump’s endorsement emerged as he took other steps to get his campaign back on track after days of controversy and falling poll numbers that have given Democrat Hillary Clinton the advantage in the race to the November 8 election.

In the latest Reuters/Ipsos poll released on Friday, Clinton’s lead over Trump narrowed to less than 3 percentage points, down from nearly 8 points on Monday.

Trump on Friday announced he was setting up an advisory team to help guide him on economic policy. The group relies heavily on hedge fund managers and investment bankers, a group Trump has railed against in the past, and includes no women.

In addition, Trump plans to release his framework for boosting the US economy in a speech in Detroit on Monday, an event that will offer him a chance to avoid theatrics and detail how he would handle economic issues if elected.

Trump stays on message … for a change

At a rally in Des Moines, Trump showed new-found discipline, mostly sticking to his central charge that Clinton is the “queen of corruption”. He defended himself against her charge that he is temperamentally unfit for the White House.

“All my life I’ve been told, ‘You have the greatest temperament’,” he said.

Trump also defended himself against what he called the news media’s claim that he kicked a baby out of an event earlier this week in Virginia. “I love babies,” he said.

Clinton sought to take advantage of Trump’s dip in the polls at a conference of minority journalists in Washington, where she pledged an all-out fight for comprehensive immigration reform if she wins the election.

At the event Clinton did what she has rarely done during the presidential campaign: take questions from reporters.

She addressed two of the largest issues that continue to dog her campaign: the controversy over her use of a private email server while she was secretary of state during the Obama administration, and continuing scepticism among voters about her trustworthiness.

Clinton conceded that she had “short-circuited” earlier in the week in interviews when she had asserted that FBI director James Comey had concluded she had been truthful in her statements about use of the private server.

She maintained that “I never sent or received anything marked classified”, while acknowledging that some material she sent may retroactively have been considered classified by other government agencies.