SALZBURG, Austria (Reuters) - Austria’s Greens on Saturday formally approved a coalition deal with conservatives led by Sebastian Kurz, backing their leader’s argument that it would keep the far right out of power and bring ambitious environmental reforms despite misgivings.

The parties struck the deal on New Year’s Day, paving the way for Kurz to return to power three months after winning an election and for the left-wing environmentalists to enter government for the first time.

President Alexander Van der Bellen will swear in the new government on Tuesday, his office said.

The awkward alliance is being closely watched in Germany, where the electoral balance is similar, at a time of growing calls for urgent action on climate change.

Many Greens have balked at elements of Kurz’s law-and-order agenda, despite their leader Werner Kogler saying the deal had to reflect their party’s smaller share of the vote. The Greens won 13.9% compared to 37.5% for Kurz’s People’s Party (OVP), whose last coalition was with the far-right Freedom Party (FPO).

“The future is made of courage. Yes but also of the force of will, of a plan,” Kogler told a party congress whose approval he needed to seal the coalition deal. He added that it “makes a difference” whether Kurz governs with the Greens or the FPO.

He received a standing ovation and repeated applause before 93% of delegates backed the deal in a show of hands.

Kurz has made a hard line on immigration and “political Islam” his trademark, and the deal includes extending a ban on headscarves in schools until the age of 14 from around 10 currently.

The OVP-FPO coalition collapsed in May when FPO leader Heinz-Christian Strache was caught in a video sting offering to fix state contracts. A provisional government of civil servants has been in place since June.

MAKE IT SO

The new coalition deal resurrects some of the previous Kurz government’s ideas such as preventive custody for people deemed a threat to public safety, proposed after a fatal stabbing apparently committed by an asylum seeker.

Many Greens expressed misgivings.

“It is not enough to say that we blocked the FPO,” Flora Lebloch from the party’s youth wing said, calling Kurz’s OVP “an authoritarian right-wing party”.

The dominant mood, however, was one in favor of compromise.

“Sometimes you have to work with the Klingons,” one delegate from the eastern province of Burgenland said in a Star Trek-themed speech, arguing the party should “boldly go where no Greens have gone before”.

Another contentious point is that the Greens’ plan to overhaul taxation to better price in planet-warming carbon emissions has been put off until 2022.

“What will happen in 2022? I don’t know yet either,” said Kogler. “But we will work on it and fight for it to move forward.”