Russia's Supreme Court on Monday upheld a decision barring the anti-war Yabloko party from parliamentary elections in September.
The court, presided over by Vladimir Saizev, rejected the liberal opposition party's appeal against last week's ruling.
Yabloko's prospects of success had been considered slim from the outset. The party said it would now lodge a supervisory appeal with the Presidium of the Supreme Court.
Party leader Nikolai Rybakov had called on the court to reinstate Yabloko's registration for the September 18-20 election, which had been approved by the Electoral Commission in July.
On August 10, the court upheld a complaint by the pro-Kremlin ultranationalist Rodina party, which accused Yabloko of violating Russia's electoral laws.
It was the first time in Russia that a party already cleared to take part in an election had subsequently been excluded. A three-judge panel upheld that decision on Monday.