Leo Varadkar returned as taoiseach, or prime minister, of Ireland on Saturday, replacing Micheal Martin as part of an unconventional coalition deal struck more than two years ago.

Varadkar's nomination was approved by lawmakers during a special session of the Dail, the lower house of parliament. Varadkar later received the seal of office from President Michael D. Higgins.

Why is Varadkar back as taoiseach?

Following Ireland's election in February 2020, the two largest political forces, the center-right Fine Gael and Fianna Fail agreed on a three-way coalition with the smaller Green Party.

The two fierce rivals, who were on opposing sides in the Irish Civil War in the early 20th century, had not participated in the same government since independence in 1922.

Fine Gael and Fianna Fail came together after the left-wing nationalist party Sinn Fein, which won the largest share of votes, failed to get enough support to govern.

The two parties have long refused to share power with Sinn Fein because of its historic links to the Irish Republican Army and decades of violence in neighboring Northern Ireland.

Under their coalition agreement, struck four months after the election, Fine Gael and Fianna Fail agreed to share the role of taoiseach.

Fianna Fail's Martin was appointed for the first two-and-a-half years and Varadkar held the deputy premier role.

Martin now takes the deputy role and is expected to become foreign minister, while Finance Minister Paschal Donohoe and Public Expenditure Minister Michael McGrath will also swap roles.

Varadkar served as prime minister between 2017 and 2020, becoming the country's youngest-ever leader at 43 and the first openly gay prime minister.

His ascent to the top of Irish politics was remarkable for a country dominated by a strict, conservative Catholic morality well into the latter half of the last century.

With an Irish mother and Indian father, he was also Ireland's first mixed-race taoiseach.

How was the handover of power?

During a special sitting of the Irish parliament in Dublin, Varadkar paid tribute to Martin, who he said had provided "reassurance and hope in difficult times."

"I accept this nomination with humility and resolve and a burning desire," he said, adding he wanted "to provide new hope and new opportunities for all our citizens."

Martin, meanwhile, said in a video posted to social media that it had been "the honor of a lifetime" to serve as taoiseach and he was "looking forward to the second phase of this government."

However, Sinn Fein leader Mary Lou McDonald voted against Varadkar's selection, saying the coalition was "out of touch, out of ideas and out of time."

Her party has led opinion polls by around 10 percentage points for over a year and is particularly popular with younger voters.

What will be Varadkar's priorites?

Varadkar's first tenure as taoiseach was overshadowed by Brexit and COVID.

During the pandemic, he re-registered as a doctor and returned to work once a week while continuing to lead the country.

The government now faces a daunting set of challenges, including a housing crisis, soaring energy costs and an overstretched healthcare system.

Varadkar promised to tackle the housing and cost of living crises during the remainder of the government's term.

Thorny post-Brexit relations with the United Kingdom are also expected to dominate.

Britain and the EU are in a long-running dispute over post-Brexit trade rules for Northern Ireland, a British province with a long open border with Ireland, an EU member.

mm/ar (AFP, AP, Reuters)