Hillary Clinton’s campaign running mate has said he is nervous that Donald Trump could have a “quick trigger finger” that might plunge the US and the world into a nuclear catastrophe.

Tim Kaine, the Democratic Vice-Presidential candidate during the US election, also said the President’s team contained members of the “club of the wacky” and “people who scare me to death”.

Some actions of the Trump administration, he added, had been a national embarrassment.

The only thing that could stop Mr Trump serving a full four-year term, he argued, was if now “unstoppable” investigations into what happened during the election uncovered “direct evidence of collusion between candidate Trump and Russia.”

While addressing an audience at the Chatham House international affairs think tank in London, the Virginia Senator admitted: “I am nervous about President Trump and could there be a quick trigger finger in a way where we overreact to something, and there could be something very dangerous. Absolutely.”

His admission came in response to being challenged about whether he stood by comments made in the Vice-Presidential debate with Mike Pence, during which Mr Kaine had warned: “Ronald Reagan said the problem with nuclear proliferation is that some fool or maniac could trigger a catastrophic event. And I think that's who Governor Pence's running mate is. Exactly who Ronald Reagan warned us of."

Senator Kaine also told the Chatham House audience: “There are some really sharp global figures who are part of the Trump team. [But] There are some people who scare me to death.

“Times right now make discussion of the US as the exemplary democracy a little bit challenging. Some of the events of the last months have even been a little bit embarrassing. I have been embarrassed by them.”

Attempting to strike a note of optimism, however, Mr Kaine suggested that the “club of the mature” might prevail over “the club of the wacky” within the Trump administration.

“That’s why I have been so quick to support some of the Trump cabinet nominations,” he said. “General [James] Mattis is going to be the right kind of person to be Secretary of Defence. General [John] Kelly is going to be the right kind of person to be head of Homeland Security.

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“And I can tell you I have got uninterrupted nights of sleep since [Mike] Flynn has gone [as National Security Advisor].

“Trump’s not going to change his personality, but he does have people around him that are smart folks. I voted against Rex Tillerson for Secretary of State for a variety of reasons, but I think he’s going to join the club of the mature rather than the club of the wacky.”

Speaking as Mr Trump used his address to the Conservative Political Action Conference to launch a fresh attack on the media, Senator Kaine said it was now impossible for the administration to dodge the questions about possible links between the President’s associates and Russia.

Mr Kaine said: “The resignation of General Flynn fundamentally changes it. This is now in the White House, that the National Security Advisor was having back channel discussions with Russians, in the lame duck sessions and after inauguration.

“If people want to sweep it under the rug, they can’t. This is now in the White House. And that really guarantees that - it will probably be slow and halting, there will probably be efforts by some of the Republican side to try and stop it - but it’s not going to be stopped.

“We now have a momentum, together with a very engaged press. We will get to the last question: ‘What was the level of collusion - if any - between the Trump campaign and the Russians in the effort to cyberhack the American Presidential election?’ We will get to the answer.”