UPDATE 1 — Swedish parliament votes against Social Democrats leader as PM, as expected

(Adds quote, detail on vote, background in bullet points) STOCKHOLM, Oct 15 (Reuters) — Sweden's parliament on Thursday rejected Social Democrats leader Magdalena Andersson's bid to form a minority government, as widely expected, extending a period of uncertainty over who will become prime minister after last month's general election. Four centre-left opposition parties, which have all said they favour Andersson as prime minister, on September 13 won a majority of seats in Sweden's parliament, the Riksdag, but do not agree on who should be part of a new government. The opposition in September won 176 seats to 173 for Prime Minister Ulf Kristersson's right-wing bloc. Thursday's ballot was the first of up to four votes before a new election must be called "It's been clear to me since the election night that it will take some time and that several ballots would likely be necessary to appoint a prime minister," Andersson told reporters after the vote in parliament Only the Social Democrats voted in favour of Andersson, while the other parties voted against The parliament speaker is widely expected to next ask Kristersson of the Moderates -- the second-biggest party after the Social Dem