Athens: Underestimating Kyriakos Mitsotakis has been something of a national sport in Greece.

“Koulis,” his detractors spit out, using a common diminutive of his first name that is usually reserved for children, as they mock a barely noticeable lisp.

But after sweeping to victory in a general election Sunday, it seems Mitsotakis, the leader of the centre-right New Democracy party, may have the last laugh.

His ascent to become Greece’s prime minister is testament to his tenacity, and to the radical shifts the country’s political system has undergone amid a decade of extreme financial hardship and the ensuing recasting of political alliances.

It is also a striking resurgence for a mainstream political party at a time when European centre-right parties are struggling to win elections convincingly and form governments without coalition partners.

The youngest of former Prime Minister Konstantinos Mitsotakis’ four children, Kyriakos Mitsotakis, 51, will have to convince a sizeable chunk of the Greek population that he is up to the task of leading this exhausted nation into better times. He will need to win over those who believe he lacks the competence to deal with the complexities of Greece’s huge economic and social challenges.

It may not be easy.

“He has the brain of a 5-year-old,” a group of young men drinking iced coffees in the northern town of Veroia said almost in chorus just after Mitsotakis made a campaign stop there. But they couldn’t explain why they thought that, and just cited the candidate’s mannerisms: “Have you seen how his eye twitches?”

Mitsotakis earned a bachelor’s degree at Harvard and a master’s at Stanford before returning to Harvard for a master’s in business administration. He worked at Chase Investment Bank and McKinsey and Co., a consulting firm, in London, before deciding to try his hand at politics.

He says that his last name helped him with his first election as a member of Greece’s parliament, but that, if anything, it has increasingly been a burden. “I don’t see people voting for me for coming from a political family,” he said in a recent interview. “I see people voting for me despite me coming from a political family.”

Yet it may be fair to say that he might never have become prime minister had he not been his father’s son. Liberals in Greece are considered something of an oddity, and hardly ever make it into parliament.

“His family name and connections gave him a path to politics,” said Nick Malkoutzis, editor of the economic analysis website MacroPolis. “But as leader of New Democracy, he has carved out his own space, advocating liberal policies that until recently were anathema to Greek voters and politicians alike.”

Mitsotakis says he is amused by the slurs used against him, and attributes them to dirty politics by his main opponent, the departing prime minister, Alexis Tsipras.

“It’s true neocommunist style,” Mitsotakis said, “and I simply laugh about these comments coming from someone who hasn’t worked a day in his life and took 10 years to graduate from university.”

Tsipras completed a bachelor’s degree in civil engineering in 2000, about eight years after enrolling in university, and went on to earn a master’s in urban planning. He briefly worked in the construction industry, but he became involved in youth politics while still at university and quickly pursued that full time.

Mitsotakis originally faced significant internal opposition to becoming New Democracy’s leader 3 1/2 years ago. As someone who supports private enterprise and has voted in favour of LGBT rights and a less stringent approach on migration, Mitsotakis had to win over the party’s traditionalists, conservatives and right-wingers who espouse nationalist positions and are largely anti-gay and pro-church, while also often supporting a more interventionist state in citizens’ lives.

But the party needs him, too. With racist, populist and anti-Semitic commentary common among New Democracy’s older guard, Mitsotakis ultimately came to be seen as someone who could reform the party and improve its image to make it electable.

“If the party is a broad church, then it only has one priest,” Mitsotakis said. “It was my job to keep it united and at the same time to ensure that I transform it into a modern liberal party.”

It will be a tall order, especially when pushing through unpopular measures such as evaluating the performance of civil servants.

“Mitsotakis’ premiership will be defined by whether he can show the necessary leadership skills to seize the moment, including vis-a-vis his own party,” said Malkoutzis, the MacroPolis editor. “That will be where Mitsotakis will have to weigh things up: whether the importance of a reform outweighs its political costs.”

It will take deft leadership to keep the discipline after this watershed victory, and some of Mitsotakis’ biggest challenges could come from within his party, where entrenched factions continue to support vested interests.

Yet a worn-down electorate that has endured 10 years of record-high unemployment, failed social services, diminished salaries and pensions, and the constant scorn of Europe has decided to take a chance on Mitsotakis.

At the party headquarters one recent morning, young experts with doctorates from some of the world’s best universities rubbed shoulders with smoking, cursing party apparatchiks, as three Greek Orthodox priests visited. It was an apt snapshot of this time of change for New Democracy, and for Greece, that Mitsotakis hopes to oversee.