Outgoing UKIP leader Nigel Farage has urged Republicans to “get your walking boots on” and drum up support for Republican presidential nominee Donald Trump.
He appeared before 15,000 activists in Jackson, Mississippi, being introduced by and sharing the stage with Trump.
And he said the party could “beat the pollsters” in the presidential race.
Trump, who is trailing his rival Hillary Clinton in the opinion polls, backed the UK’s exit from the EU.
In a tweet last week, Trump said: “They will soon be calling me Mr Brexit.”
Trump introduced Farage as the man who “brilliantly” led the UK Independent Party’s campaign to secure a vote on the future of the UK’s 40-year membership of the European Union.
Farage began his address by saying he had a “message of hope and optimism” for the Republican Party.
He drew on parallels between Trump’s bid for the White House and that of the Brexit campaign’s “people’s army of ordinary citizens”, which he said engaged successfully with the public prior to the UK’s referendum vote on whether to leave the EU.
He told those gathered: “If you want change in this country, you better get your walking boots on, you better get out there campaigning.
“And remember, anything is possible if enough decent people are prepared to stand up against the establishment.”
Farage also said the Republican campaign represented a “fantastic opportunity”.
He added: “You can beat the pollsters, you can beat the commentators, you can beat Washington.”
Farage, who attended the Republican convention in Cleveland last month, had previously said he would not “fall into the trap” of personally endorsing Trump in his quest to reach the White House, reports the BBC.
However, during his rally appearance he said that if he were an American, he would not vote for Mrs Clinton “even if you paid me”.
The UKIP leader earlier told local radio in the state that the similarities between Brexit and the US election were “uncanny”.
Speaking on Super Talk Radio in the US state, Farage said he had been part of a “political revolution” in the UK and there were the makings of a similar movement in the US.
He compared the federal government in Washington DC to the European Commission, saying many people felt it had become “its own country”, and claimed the Democrat nominee, Hillary Clinton, epitomised the status quo.
“I’m going to say to people in this country that the circumstances, the similarities, the parallels, between the people that voted Brexit and the people that could beat Clinton in a few weeks’ time here in America are uncanny.”
He suggested it did not matter that the political establishment, including many top Republicans, were shunning Trump’s campaign, because “millions of people never voted for the Bushes, who never voted for the Clintons, who haven’t voted for anybody, but who may, if they think in this presidential election they can actually change their lives and their communities, and that’s the audience that matters”.
Farage, who is credited with securing the referendum on the UK’s membership of the EU and helping to pull off the surprise Leave victory, is standing down next month as the party’s figurehead after fulfilling his lifelong political ambition, but will remain as a member of the European Parliament.
UKIP donor and strategist Arron Banks, who is travelling with Farage, suggested on social media that he would be having dinner with Trump and was looking forward to the rally.
But Farage’s association with Trump has not gone down well with some senior members of UKIP, including its sole MP Douglas Carswell, who tweeted “it’s all going a bit South Thanet for the US Republicans” – a reference to Farage’s failed attempt to win a seat in the Kent constituency last year.
And Suzanne Evans, the former UKIP policy chief currently suspended by the party, suggested Farage was trending on Twitter “for all the wrong reasons”.
