Future governments would have to be “humble” to survive, said Sweden’s centre-right frontrunner in the country’s September 9 general election. His comment suggests negotiations on a new ruling coalition would be the hardest in modern times amid a rise in the far right.

“I’m not going to set out my conditions in advance. I note that we have a responsibility to our voters to try to implement our policies and do the best we can,” Moderate Party leader Ulf Kristersson told Reuters, cautioning against high expectations.

“It is a whole new parliamentary situation,” Kristersson, 54, a soft-spoken pragmatist, said in an interview at party headquarters in an upscale district of downtown Stockholm.

“Every new government will need, by Swedish standards, to be a humble government which understands that it is the parliament that holds the power, not the government.”

As reported by the Reuters news agency, the Sweden Democrats, founded in part by white supremacists in the 1980s, are now backed by one in five voters and will sorely test any new prime minister’s ability to form a viable government.

Negotiating directly with the far-right Sweden Democrats, whose message that immigration is tearing apart the country’s generous welfare state has polarized politics, remains officially out of the question for rival parties.

The Sweden Democrats have said they will act to bring down any government that does not listen to them, leaving Kristersson with a precarious path to winning and holding power.

According to Reuters, Prime Minister Stefan Lofven’s Social Democrats have around 25% support in polls, ahead of the Moderates and Sweden Democrats, but neither his centre-left bloc nor the rival Alliance look likely to garner a majority on September 9.

Complex parliamentary arithmetic indicates Kristersson will succeed in ousting Lofven in a post-election vote by MPs, but he will have a tough task filling the Social Democrat’s shoes.