By Gergely Szakacs
BUDAPEST (Reuters) - Hungary's far-right Jobbik party has snatched a parliamentary seat from Prime Minister Viktor Orban's center-right Fidesz in a by-election in western Hungary on Sunday, preliminary results showed.
Orban, an avid soccer fan, conceded defeat on his Facebook page, saying: "There are times when the ball hits the post."
Even with the narrow defeat, Orban will retain a comfortable majority in parliament, but the result -- the second straight by-election loss for Fidesz in two months -- could be a warning sign after the party won national, local and European elections last year.
With 99 percent of the votes counted, the National Election Office put Jobbik candidate Lajos Rig at 35.3 percent, Fidesz candidate Zoltan Fenyvesi at 34.4 percent and Socialist Ferenc Pad at 26.3 percent.
The parliamentary seat became vacant after the death of Fidesz lawmaker Jeno Lasztovicza in January.
The results however were too close for a definitive call as the number of absentee ballots was higher than the difference between the leading candidates. State news agency MTI said the final tally may only be announced on Thursday.
"We have scored a historic victory, I might even say that an era has come to an end today," Jobbik leader Gabor Vona told supporters in a video posted on news website index.hu.
Vona, who made a career vilifying Hungary's large Roma population, has softened his rhetoric and is wooing mainstream voters, rather than marginal groups.
Jobbik has also benefited from a series of policy missteps by Orban and a perception that senior officials around him are using their posts to enrich themselves.
In February an independent candidate supported by the leftist opposition won a seat in Veszprem in western Hungary, previously held by Tibor Navracsics, who was appointed European Commissioner.
A senior Jewish leader warned on Sunday that Jobbik was damaging Hungary's image as thousands rallied in Budapest to pay tribute to the hundreds of thousands of Hungarian Jews killed during the Holocaust.
(Reporting by Gergely Szakacs, editing by David Evans)