An ally of Prime Minister Vladimir Putin was on course to become the speaker of Russia's upper house of parliament after a landslide victory in a regional election denounced by the opposition as fraudulent, according to Reuters. St Petersburg Governor Valentina Matviyenko, 62, won more than 95 percent of ballots cast in each of the two municipalities in Russia's second city, which voted for a single seat on Sunday in the Federation Council. President Dmitry Medvedev has backed Matviyenko to take over the vacant position of head of the Federation Council, but she had to secure a seat in the upper chamber to be eligible for the job. Medvedev on Monday accepted Matviyenko's resignation as St Petersburg governor and appointed former KGB officer Georgiy Poltavchenko as acting governor. Poltavchenko was appointed as the president's representative to the Central Federal District in 2000 after heading the St Petersburg tax police throughout most of the 1990s, according to his biography on the Kremlin website. Matviyenko still faces an election in the Federation Council before becoming the first woman to lead the upper house, a 166-seat chamber comprising regional representatives, but the Kremlin's support makes her victory likely. Political analysts said moving Matviyenko into a new job may be intended to help win more votes for Putin's United Russia party in St Petersburg in a parliamentary election in December because she had faced criticism from local voters. The move also appears intended to ensure the loyalty of the Federation Council speaker, the third-ranking job in Russia under the constitution, before the parliamentary election and a presidential vote in March. Analysts said Poltavchenko was not among those previously known to be eyed for the post and may not stay there for long. "It is unexpected news, but I think that it means that within the ruling elite of this region, which is very influential, there was a serious struggle," political analyst Valery Khamyakov told RIA news agency. "I think that we may see another shuffle from Poltavchenko to put someone else in the post who can do more will be able to give United Russia better ratings," he said. United Russia engineered the removal of speaker Sergei Mironov, head of the Just Russia party, in May in a sign that Putin's party had lost faith in him even though he was long considered loyal to the prime minister. Boris Nemtsov, an opposition leader, said Sunday's vote was unfair because only candidates loyal to Matviyenko had been able to run against her and police had detained government critics who protested during the election. "This is a 100 percent fraud, not a vote," Nemtsov wrote in his Livejournal blog. The huge margin of victory -- officials results showed she won more than 95 percent and just over 97 percent of votes in the two municipalities -- is extremely unusual for St Petersburg. Matviyenko had angered residents of the imperial-era capital by backing plans, scrapped last year, to build a 403-metre (1,322 foot) skyscraper to house the headquarters of state-controlled gas giant Gazprom near the historic city centre. In office since 2003, she had also been criticised over deaths and injuries from ice falling from rooftops in winter.