Trump’s Helsinki press conference with the Russian president, at which he failed to challenge Putin over allegations of election meddling, has unleashed a torrent of bipartisan outrage.

Paul, however, gave a series of interviews defending the president against what he said was knee-jerk criticism from both Democrat and Republican ranks – and approving his stated strategy of re-engagement with Putin’s Russia.

“This is truly the Trump derangement syndrome that motivates all of this,” the Kentucky Republican told CNN.

“Thank you @RandPaul, you really get it!,” Trump tweeted in response.

“The President has gone through a year and a half of totally partisan investigations – what’s he supposed think?” he added, appearing to paraphrase one of Paul’s several interviews.

Trump stunned US political allies and foes alike with his answer to a question about Russian interference in the 2016 election which saw him defeat Democrat Hillary Clinton.

Putin “just said it is not Russia. I will say this: I don’t see any reason why it would be,” Trump said.

That came three days after the US Justice Department indicted 12 Russians for hacking Democratic Party computers, the latest in a series of actions taken in retribution for what US intelligence agencies say was a broad plan to support Trump’s election campaign directed by Putin himself.

Astonished lawmakers lined up to condemn Trump, with Republican House Speaker Paul Ryan reminding Trump that “Russia is not our ally” while veteran Senator John McCain said Trump’s seeming acceptance of Putin’s denial was a historical “low point” for the presidency and the summit a “tragic mistake”.