Trump Pence
Republican presidential candidate Donald Trump and VP running mate Mike Pence take the stage during a campaign rally at Grant Park Event Center in Westfield, IndianaGetty Images

In what has been a bad week for Donald Trump in the polls, the GOP candidate was hit with yet another curve ball after his running mate Mike Pence endorsed house speaker Paul Ryan.

Ryan, who is running against Paul Nehlen in Wisconsin's 1st district Republican primary election, was slow to endorse Trump and largely avoided mentioning him in his Republican Convention speech.

In addition, Ryan disavowed comments made by Trump about the Muslim family of a US fallen soldier – an incident that caused Trump's numbers to fall and further underlined the distance between Trump and Ryan – and indeed other establishment figures in the party.

But Trump's VP running mate Pence has long been an ally and friend of Ryan, and endorsed him after asking permission from Trump, despite the fact that Trump said in a CNN interview he was 'not quite there yet' when it came to endorsing Ryan.

However, Trump said he was happy for his running mate to endorse Ryan.

"[Pence] came to me, he called me, because he likes Paul Ryan, Paul Ryan's a good guy," Trump said at a rally in Maine as the crowd booed, TPM reported. "Nope, he's a good guy."

"Mike called me, and he said yesterday, 'Would you mind if I endorsed? I won't do that if it's going to cause any complications, I would absolutely not do that. He's the greatest guy, the greatest human being."

He added Pence had told him: "'I like [Ryan]. He's a friend of mine. Would you mind if I endorsed him? And I will not do it if you say no.' I say, 'Mike, you like, him, yes. Go ahead and do it, 100%.' And he endorsed him."

Trump is still struggling to regain ground lost during the Democrat Convention and following the fallout from his comments towards the Khan family who spoke out against him at the event.

His comments caused a further rift between Trump supporters and longstanding members of the party, with Ryan and Senator John McCain among a handful of people who publicly distanced themselves from Trump following the incident.