VLADIVOSTOK, Russia (Reuters) - A regional election in Russia’s Far East will be re-run, the local election commission said on Thursday, dealing a rare blow to the Kremlin after allegations the vote had been rigged in its candidate’s favor.

The ruling, in Russia’s Primorsky Region which includes the Pacific port of Vladivostok, 6,400 km (4,000 miles) east of Moscow, came a day after Russia’s top election official recommended that the election be re-run.

Ella Pamfilova, head of the Central Election Commission, had not accused the Kremlin-backed candidate, Andrei Tarasenko, of orchestrating the vote-rigging, but had said that a raft of irregularities had been identified, including ballot stuffing and vote buying.

“We believe that in the circumstances it is not possible to reliably understand the result of the will of the people, which means we can’t declare either of the candidates elected,” Tatyana Gladkikh, the chairwoman of the local election commission, said on Thursday.

The new election must be held within three months of the annulled Sept. 16 vote.

Tarasenko’s struggles and three other reversals in elections to select regional governors this month amount to the worst showing for Kremlin-backed candidates since 2012.

Though there is no immediate threat to the ruling United Russia party’s grip on power, it suggests growing discontent over living standards, not least plans to delay the retirement age, which have also been reflected in declining popularity ratings for President Vladimir Putin.

The decision to re-run the election was made after Communist Party supporters took to the streets of Vladivostok to protest after Tarasenko mounted an improbable comeback in the final stages of counting to edge out his Communist challenger Andrei Ishchenko.

Ishchenko said on Thursday he disagreed with the decision to have a re-run and judged he should be declared the winner of the original vote. The Interfax news agency cited him as saying he would try to overturn the ruling for a re-run via the courts.

Tarasenko, the Kremlin-backed candidate, said the ruling to re-run the election was fair, saying there had been too many complaints.

With just under 99 percent of votes counted on Sunday night, Tarasenko was trailing Ishchenko by more than 2 percentage points.

But on Monday, the local election commission said Tarasenko had won by just over 1 percentage point, with results showing he had received almost every one of the final 20,000 votes counted.