Danish Prime Minister Mette Frederiksen’s Social Democrats suffered heavy losses in Tuesday’s nationwide local elections, losing key cities including Copenhagen for the first time since 1903.

“We had expected losses, but the decline appears to be greater than we had expected,” Frederiksen told supporters at a party event in the Danish capital. “That is, of course, not satisfactory.”

Although the Social Democrats remain Denmark’s most popular political group, securing around 23 percent of all votes, support for the party declined in 87 of the country’s 98 municipalities.

The prime minister said she took “responsibility” for the electoral debacle, and said that she would “carefully consider what is behind it.” With Denmark required to hold general elections within the next year, the losses in Copenhagen and other Danish cities are likely to put pressure on Frederiksen to change course on some of her signature policies during the coming months.

The liberal Venstre group now controlling the largest number of mayoralties in Denmark underscores the political disaster suffered by Frederiksen’s party, whose electoral base is supposed to be made up of urban voters.

The high cost of housing dominated the campaign in Denmark’s largest municipalities, with voters exasperated by the national government’s response. In Copenhagen, where home prices have risen by 20 percent over the past year, just 12.7 percent of electors backed the prime minister’s party.

After 122 years of Social Democrat rule in Copenhagen, the party’s candidate, Pernille Rosenkrantz–Theill, was not even invited to attend negotiations to form the capital’s next government. Sisse Marie Welling — whose Socialists made the largest gains in the election — will be Copenhagen’s new lord mayor, leading a “green and progressive majority.”

Welling has tapped Line Barfod, whose Red-Green Alliance secured 1 out of every 5 votes cast in the capital, to be Copenhagen’s environment czar. That poses a major threat to the government’s controversial Lynetteholm artificial island project, which is meant to protect the city from flooding and create space for new housing. Barfod is a longtime opponent of the €2.7 billion scheme and she’s likely to make much of a new report showing the project is leaking cyanide into Copenhagen’s waters.

Beyond the capital, the Social Democrats suffered dramatic reversals in traditional bastions like Frederikshavn, where support for the party fell by half. The far-right Danish Democrats performed well in rural municipalities in Jutland, and won more seats than the number of candidates they had running for office in places such as Lolland.

While the prime minister — whose birthday is Wednesday — said that local factors had contributed to the defeat, she acknowledged that there were “also trends that transcend local conditions.”

Beyond debates over classic urban issues like mobility policies and access to green spaces, the local elections were seen as a referendum on the rightward turn the Social Democrats have taken at the national level. Based on the results, voters in major cities appear to be souring on Frederiksen’s tough stance on migration and her willingness to ally with economic liberal parties.