Pony-tailed former university professor Pablo Iglesias burst onto Spain's political scene seven years ago as the country was still grappling with the fallout from the global economic crisis.
His party has come a long way from its beginnings in the anti-austerity "Indignados" protest movement that occupied squares across Spain, with his hard-left Podemos party entering parliament in 2015 and eventually becoming part of the government just over a year ago.
But on Monday, the 42-year-old political scientist dropped a bombshell, saying he was resigning from government to run for election as Madrid's regional leader.
The move comes with Podemos languishing in the polls, a far cry from its beginnings in January 2014 when Iglesias and colleagues from Madrid's Complutense University channelled the widespread anger over austerity and inequality into a potent political force.
In its first legislative elections in December 2015, the party came third, and did the same in June 2016, upending the traditional hegemony of the rightwing Popular Party and the Socialists.
In January last year, the party joined the Socialists in forming Spain's first coalition government since the end of Francisco Franco's dictatorship in 1975
And Iglesias, who wears open-necked shirts at official events and wears his long hair tied back in a bun or ponytale, was sworn in as a deputy prime minister.
"In politics you must have courage, courage to understand when the time has come to make way for other leaders," he said in announcing his decision to resign on Monday.
Over the past 14 months, Spain's leftwing coalition has been blighted by disagreements on issues ranging from migrants to ending the monarchy.
Torn between his role as both ally and rival of the Socialists, Iglesias can now "more comfortably keep one foot inside the government and one out, to dedicate himself to political criticism," said political analyst Pablo Simon.
- From protester to politician -
Bearded and with a solemn gaze that is regularly broken by a winning smile, Iglesias was raised in the working-class Madrid neighbourhood of Vallecas.
His mother was a labour lawyer and his father a work inspector who was jailed during Franco's dictatorship.
Immersed in politics from an early age, Iglesias was active in the Communist youth and anti-globalisation movements before the Indignados protest movement erupted in Spain in 2011 at the height of the economic crisis.
A brilliant orator and strategist, he has often railed on Twitter and in numerous television interviews against Spain's elite "caste" of mainstream politicians and bankers.
But his dominance over Podemos has not always sat well with other founders of the party, especially in terms of strategy, prompting high-level resignations that have weakened the formation.
In 2018, Iglesias -- who in the past has boasted about buying his clothes at a low-cost supermarket -- put his leadership of Podemos to a grassroots vote following an outcry over his purchase of a luxury home with a swimming pool and guest house in the mountains near Madrid.
- Chavez adviser -
Iglesias once served as an advisor to the late Venezuelan president Hugo Chavez, and has been accused of using money from Caracas to fund his political ventures in Spain.
His vehement speeches have divided opinion, with some business leaders and the rightwing press seeing him as a dangerous populist.
But he also comes across as both funny and accessible, playing his guitar live on television, giving a presenter a ride on his red scooter or quoting from "The Simpsons".
A huge fan of "Game of Thrones", Iglesias defied protocol when he met Spain's King Felipe VI for the first time, handing the monarch a box set of the Emmy award-winning series.
With his partner, Equality Minister Irene Montero, he has three young children.
One of his teachers, Ramon Cotarelo, remembers him as a "caring" and "brilliant" student.
But former colleague Antonio Elorza disagreed.
"You couldn't trust him. He would do whatever he pleased.. so as not to lose an ounce of power," he said.