The anti-immigration Progress Party once favoured by right-wing extremist Anders Behring Breivik has lost a third of its vote in local polls in Norway.
Mr Breivik, who killed 77 people in a bomb and gun massacre seven weeks ago, was once a member of the party.
With nearly all votes counted, the opposition Conservatives had the biggest gains, taking 28% compared to 19% in 2007.
The governing Labour Party - targeted by Mr Breivik - made smaller gains.
It increased its vote share by two points, to reach nearly 32%.
However, it saw its coalition ally the Socialist Left Party (SV) drop from 6% to 4%, compared to the 2007 local election results.
Mr Breivik has confessed to killing 77 people and injuring 151 on 22 July, in a bomb attack on government offices in Oslo and a shooting spree on the island of Utoeya, where the Labour Party youth wing was holding a summer camp.
Mainstream politicians had urged voters to show their contempt for the far-right at the polls, held over two days, Sunday and Monday.
The populist Progress Party, which has campaigned to tighten restrictions on immigration, saw its support fall to 11.4% from 17.5% in 2007.
Its leader, Siv Jensen, blamed the poor result on national revulsion over the attacks by Mr Breivik, a former member of her party.
The party has distanced itself from Mr Breivik's actions and extreme views.
Analysts say a sex scandal earlier this year may have also cut into the party's support.
They say the Conservative Party is now well positioned to challenge the Labour Party at the 2013 general election.
"The Conservatives are the big winners," said Haavard Narum, political columnist at the newspaper Aftenposten.
He attributed the party's best result in local elections since 1979 to voters who had abandoned the Progress Party.
Before the July attacks, the Labour Party had been expected to lose ground in the vote, but in fact made gains of 2%. Analysts said this may have been because of a sympathy vote, or endorsement of the way Prime Minister Jens Stoltenberg had handled the tragedy.
With SV suffering losses proportionally as heavy as Progress, its leader, Kristin Halvorsen, announced she would step down early next year.
Columnist Mr Narum said the departure of the SV leader could shake the Labour-led coalition, which also includes the Centre Party.
However, Prime Minister Jens Stoltenberg said he felt "secure" his government would last until 2013.