Former President Donald Trump added his voice to growing demands for an audit of votes cast last year in Pennsylvania, inspired by a partisan effort to overturn results in Arizona.

Three state lawmakers from Pennsylvania this week visited the Arizona State Fairgrounds, site of a former basketball arena, where a hand count of 2.1 million ballots is under way.

They are the latest Republicans to make the journey as part of a growing movement to overturn Trump's defeat.

The former president described them as 'great patriots' on Friday, demanding that the Pennsylvania state senate sets up its own audit.

'The people of Pennsylvania and America deserve to know the truth,' he said.

'If the Pennsylvania senate leadership doesn’t act, there is no way they will ever get re-elected.'

Pennsylvania Sens. Doug Mastriano and Cris Dush, and Rep. Rob Kauffman visited Arizona on Wednesday.

They met local state legislators before joining Doug Logan, the head of Cyber Ninjas, which is leading the audit, for a tour of the audit site.

Mastriano told WEEO radio: 'We’ll bring the information back to the Senate leadership, we’ll back-brief them on the way ahead and then hopefully we can come up with an approach here to make sure every person in Pennsylvania can rest assured they have one vote and it counts.'

Trump lost Arizona by about 10,000 votes. He and his allies alleged that fraud cost him the state.

Arizona Senate Republicans used their subpoena power to access to ballots, counting machines and electronic data in Maricopa County, home to about 60 percent of Arizona’s voters, for an audit.

However, the recount has been criticized as chaotic: auditors searching for watermarks were told by state election officials the ballots were not watermarked; reports suggested they were also looking for traces of bamboo as evidence the papers were smuggled in from Asia.

But for a steady stream of Republicans the audit is seen as a model for what could be done in other closely contested states

'I wouldn’t be surprised if they found thousands and thousands and thousands of votes. So we’re going to watch that very closely,' Trump told a crowd at Mar-a-Lago recently.

'And after that, you’ll watch Pennsylvania and you’ll watch Georgia and you’re going to watch Michigan and Wisconsin.'

Yet people close to Trump have been advising the former president not to get too closely involved.

They would prefer him to look ahead, building a policy platform for next year's midterms, rather than backwards.

'It's not something we want to make a lot of noise about right now because Arizona might be a big nothing burger,' said one recently.

But after weeks of silence, Trump has begun to take a closer interest, praising the Pennsylvania lawmakers and demanding a similar review in a state he lost by about 80,000 votes.

In the meantime, some of his most high-profile - and most controversial - supporters have made a beeline for the Arizona recount.

Reps. Marjorie Taylor Greene and Matt Gaetz stopped off on their America First tour two weeks ago.

'We are here in Arizona to stand in solidarity with the Arizona election audit,” Gaetz told a crowd of several hundred Trump supporters, adding that he hoped it would be the start of a bigger movement.

He said: 'It’s my belief that Arizona will be the launch pad for elections audits and election integrity efforts all over this great country.'