Scotland’s leader is facing a difficult battle to remain in power after ending a three-year agreement to share power with the Scottish Green Party following a disagreement over climate change policies. The decision on Thursday by the leader of the Scottish National Party to abruptly cancel the deal with the much smaller Greens party, which both support Scotland’s independence from the U.K., has triggered a series of events that could see him lose his top job next week and possibly lead to an early election.

The termination of the 2021 agreement between the two parties known as the Bute House Agreement prompted the main opposition party in the Edinburgh-based parliament, the Conservatives, to say they will put forward a vote of no confidence in the first minister next week. If all opposition legislators, which now include the Greens, vote against him, the leader would lose and he would come under huge pressure to resign, which could set the stage towards an early election — the next Scottish parliamentary election isn’t scheduled until 2026. Of Parliament’s 129 seats, the SNP holds 63, two short of a majority.

The Greens confirmed late Thursday that they would be voting against the leader, along with the other main opposition parties, including the Conservatives and Labour. “We no longer have confidence in a progressive government in Scotland doing the right thing for climate and nature,” co-leader Lorna Slater said. The leader, who replaced long-time leader Nicola Sturgeon, may need the vote of a independent legislator, to survive. She has indicated that she would seek to extract a price from the leader in order to back him in the no-confidence vote.

Her backing would result in both sides having 64 votes, meaning that the chamber’s presiding officer — Scotland’s equivalent to the speaker — would cast a tie-breaking vote. In that scenario, Alison Johnstone would be expected to vote in favor of maintaining the current administration.

The announcement by the Greens capped a dramatic day in Scottish politics. Relations between the SNP and the Greens, which both back Scotland’s independence from the U.K., soured recently, particularly in the last week after the leader abandoned a key climate change target, specifically the goal of reducing emissions by 75% by 2030, arguing that it was “beyond what we are able to achieve.” Many members of the Greens were furious at the decision, and a vote was planned on whether it would continue to participate in the government. The leader denied he was ending the agreement to prevent a vote to end the coalition.

“It is no longer guaranteeing a stable arrangement in Parliament — the events of recent days have made that clear, and therefore, after careful consideration, I believe that going forward it is in the best interest of the people of Scotland to pursue a different arrangement,” he said at a news conference. It was a risky decision as the SNP doesn’t have a majority and, if it survives as an administration, will have to rely on votes from other parties to get legislation and the budget through Parliament.

The leader said that the SNP has often governed as a minority administration since it first came to power in 2007. The decision to end the agreement also came as the SNP has been shaken by the news earlier this month that Sturgeon’s husband, Peter Murrell, has been charged with embezzlement in an investigation into the party’s finances. Opinion polls are showing that the SNP, which has dominated politics in Scotland since 2007, is facing stiff opposition from the Labour Party as the U.K. general election draws nearer. The vote will take place sometime in the coming months. If Labour can grab a sizeable chunk of seats in Scotland, it could well be on course to win a majority, even a big one.