Anantnag: Making mincemeat of her electoral rivals, Jammu and Kashmir Chief Minister Mehbooba Mufti on Saturday won the Anantnag assembly by-poll by a margin of over 12,000 votes -- in what is seen as a first popularity test of the over year-old PDP-BJP government in the state. Mehbooba Mufti polled 17,701 votes while her closest rival Hilal Ahmad Shah of the Congress managed just 5,616 of the over 28,500 polled on June 22, an official of the election commission told IANS here. National Conference's Iftikhar Hussain Misghar came a distant third with a little over 2,800 votes in the low turnout polling -- 34 per cent -- amid a boycott call by Kashmiri separatists and militants. In Delhi, Prime Minister Narendra Modi and Union Home Minister Rajnath Singh congratulated Mehbooba Mufti on her electoral victory. Modi termed it a "phenomenal victory". The decisive victory margin for the fist woman Chief Minister of Jammu and Kashmir is seen as a public endorsement of her Peoples Democratic Party's (PDP) decision to continue its alliance with the right-wing Bharatiya Janata Party (BJP). Her rivals in the National Conference and the Congress had made Mehbooba Mufti's decision to continue the alliance with BJP a hallmark of their electoral campaign in Anantnag. The by-election was necessitated because of the death of her father, then Chief Minister Mufti Mohammad Sayeed. The late Chief Minister represented the seat in the assembly that has an effective strength of 87. Mehbooba Mufti's victory margin is double that of her father. In 2014, Sayeed won the assembly seat defeating Congress' Shah by a margin of 6,000 votes. But the voter turnout then was 40 per cent. "She has won people's endorsement for the vision of Mufti Muhammad Sayeed," a senior PDP minister told IANS. Opposition candidates alleged that the Chief Minister "engineered" her victory by using the government machinery in her favour. The Congress' Shah alleged discrepancies in some Electronic Voting Machines (EVM) as they were "not sealed properly" and that postal ballots were counted as "bogus votes". "They have changed the voting machines. This is a murder of democracy. The election observers acted as dead wood," Shah told IANS. Congress and National Conference supporters earlier created a ruckus inside the counting hall, Government Degree College, Anantnag, by shouting anti-government slogans that briefly disrupted the vote count. As election officials refused to entertain the protests, the opposition supporters led by Shah walked out and refused to be part of the counting. The PDP has termed the protest as a frustration over defeat. PDP legislator Abdul Raheem Rather told IANS that the Congress had lost from "places where they had a good support". "This is expected from them," Rather said, refuting the allegations of bogus votes. Eight candidates contested from the constituency that has over 84,000 eligible voters. Sayeed passed away in New Delhi on January 7 after a brief illness. Mehbooba Mufti assumed power after being sworn in as the Chief Minister of the PDP-BJP coalition government on April 4. It is mandatory for a Chief Minister or any other minister in the state to become a member of either house of the state's bicameral legislature within six months of being sworn in. Mehbooba Mufti represents the south Kashmir Anantnag Lok Sabha constituency in parliament. She will now give up the Lok Sabha seat with her election as legislator.