On Wednesday, Blair, who governed the U.K. between 1997 and 2007, expressed bemusement and dismay at the popularity of Trump and other polarizing politicians in the U.S. and Britain.
"Sometimes I look at politics today and wonder if I still understand it," Blair said in a conference interview at the Global Financial Markets Forum in Abu Dhabi.
He added that the rise of social media had helped create "insurgent movements that are often around very polarizing political positions."
"I get really anxious when I think that policy is being made by Twitter feed," Blair said. "Those that shout loudest do not necessarily deserve to be heard the most."
Blair led the U.K.'s Labour Party to a landslide victory in 1997 after 18 years out of power, steering the party away from socialism to the center left.
The former politician has expressed surprise at the recent success of more leftist politicians like Jeremy Corbyn in the U.K. and Bernie Sanders in the U.S., doubting their electability as country leaders.
On Wednesday, he drew parallels between insurgent, populist political movements of both the left and the right.
"It is clear that these political movements can take over parties — but can they win elections? … My bet is that in the end, the public as a whole is still more center-left and center right," Blair said.