Tony Blair has admitted to being utterly confused by the rise of Jeremy Corbyn and Bernie Sanders but acknowledged the had been a "loss of faith" among voters in more centrist leftwing politicians.
"I’m not sure I fully understand politics right now," the former Labour prime minister told The Guardian and The Financial Times.
Blair said there appeared to be a "desire to choose people who are going to rattle the cage" in both Britain and the United States.
"And it’s partly also about social media, which is itself a revolutionary phenomenon which can generate an enormous wave of enthusiasm at speed," he said.
"When I first started in politics, these things took so long to build up momentum; your decision points were well before that moment was achieved. But it’s also a loss of faith in that strong, centrist progressive position and we’ve got to recover that.”
Blair also criticised Labour Party members and Democrats who wanted to back candidates, such as Corbyn and Sanders, who he said were unlikely to be able to win national elections.
“One of the strangest things about politics at the moment – and I really mean it when I say I’m not sure I fully understand politics right now, which is an odd thing to say, having spent my life in it – is when you put the question of electability as a factor in your decision to nominate a leader, it’s how small the numbers are that this is the decisive factor. That sounds curious to me," he told the papers.
"Surely it should be a major factor because if this is not about you, but it’s about the people you want to serve, then selecting someone who is electable is really important because otherwise you can’t help people; you’re powerless."
Blair, who is a supporter of Hillary Clinton, said it was "up to the Democrats" who they nominated in the presidential race.
But drawing parallels with the British Labour Party, he said: "Five months on from the nomination of Jeremy Corbyn as leader of the Labour party, you’ve got the published polls. We [Labour] should be significantly ahead. The last poll I saw, we were quite significantly behind."
Speaking at the Center for Strategic & International Studies (CSIS) in Washington DC, Blair also directed thinly veiled swipe at Donald Trump, Blair said US presidential candidates should not attack entire religions.
“Who you elect as your president is up to you," he said. "I just want to make that clear. You guys, you can decide that."
“Let me just say I think, mentioning no names, that it is vitally important, if we are going to win this battle, that we have allies and those allies within Islam are crucial so we probably should concentrate on building those alliances not alienating an entire religion."
Trump, who won last night's Nevada caucuses and is the frontrunner for the Republican nomination, has called for all Muslims to be banned from the United States.