Members of the Pakistan Democratic Movement (PDM) celebrated Yousuf Raza Gilani's win in the Senate elections over PTI's Abdul Hafeez Shaikh on Wednesday, while the government decried the win and said that the results would be challenged.

In a blow to the government, the joint opposition candidate Gilani won the hotly contested general seat from Islamabad, beating Shaikh. Gilani secured 169 votes while Shaikh bagged 164 votes.

PPP chairman Bilawal Bhutto-Zardari took to Twitter with a succinct "Democracy is the best revenge", adding: "Jiye Bhutto."

A few hours after polling ended, Bilawal alongside Gilani held a press conference in which both leaders hailed the latter's victory as "a win for democracy".

The PPP chairperson claimed that "a new era was starting in Pakistan's democratic journey".

He thanked the PDM leadership and said that Gilani's win was a win for all democratic forces in Pakistan. "This puppet government has lost from its own parliament and the people of Pakistan have won."

"[Prime Minister] Imran Khan should resign, this is not only the opposition's demand but of the government's own members," claimed Bilawal.

Gilani thanked PDM leaders and said the movement had been successful in securing the coveted Islamabad seat.

PML-N supremo Nawaz Sharif called the win "a glorious victory".

PML-N vice president Maryam Nawaz also tweeted her congratulations to Gilani and the opposition alliance's Pakistan Democratic Movement (PDM). She commended the PML-N MNAs for accepting the party supremo Nawaz Sharif's stance and "refusing to bow down and sell out".

"Well done PML-N! The future is yours," said Maryam.

In another post, she claimed that "the fake mandate has been snatched back by the people's representatives".

"Their own people, despite the pressure on them, refused to vote for [...] (Prime Minister) Imran Khan," she said, adding that the premier now had no right to occupy the Prime Minister House.

"Vote chor (thief), leave the chair."

Sindh Education Minister Saeed Ghani congratulated Bilawal on the "historical win" of Gilani and the PDM.

PML-N senior leader Ahsan Iqbal said after Gilani's win, Prime Minister Imran should resign tonight. "Imran and his ministers can't even cast their votes properly; how can they run a country?" he questioned in a tweet.

PTI calls for investigation

Members of the government, however, criticised the results and hit back that they must be investigated.

Senator Faisal Javed termed the results "horse trading at its peak". He said the result should be "investigated and justice must be served".

"May Allah help [Prime Minister] Imran Khan eliminate corruption from this country. We are with you [Prime Minister] Imran Khan," said Javed, adding that the premier was the "sole fighter" against corruption.

Addressing a press conference, Minister for Information and Broadcasting Shibli Faraz lashed out at the opposition, saying "they should be ashamed. With what face and character can they say such things?". He was referring to reports of a no-confidence motion by the opposition.

He said the result of the election for the Islamabad seat was a "vindication of the stance that Prime Minister Imran Khan repeatedly talked about".

"You know the character of those who have won," said the information minister, adding that the prime minister was the only solution for the development and progress of the country.

Special Assistant to the Prime Minister for Political Communication Dr Shahbaz Gill said the party "will challenge this result".

He alleged that people had sold their votes on the same ballot paper for money. The prime minister was proved right, said Gill, and once again "votes were sold in the election".

"Have an auction of consciences next time instead of an election."