Following Awami National Party's exit from the Pakistan Democratic Movement (PDM), the JUI-F and PML-N Tuesday have strongly reacted to the move.
ANP took the decision after its leaders were issued show-cause notices to explain their actions during the recently-held Senate polls.
Announcing the decision at a press conference in Peshawar, ANP's Ameer Haider Khan Hoti said the PTI and the JUI-F have joined hands to give the PPP a tough time in Larkana.
Reacting to ANP's hard-hitting presser, JUI-F's secretary-general Senator Maulana Abdul Ghafoor Haideri said there were several ways to caving in and selling out.
"This is the most humiliating move in political history … ANP and PPP's actions have led to the world laughing at us," the JUI-F senator said.
"Despite all this, we went and spoke to ANP's leadership and they said the move was made based on friendly ties. However, Hoti said the party had made a wrong decision (supporting Yousuf Raza Gilani for Opposition leader in Senate)."
Haideri warned ANP it had made a "blatant" mistake after blaming PDM chief Maulana Fazlur Rehman for lacking leadership.
"ANP should not have blamed Fazlur Rehman."
Similarly, PML-N spokesperson Marriyum Aurangzeb said ANP had made several sacrifices for the cause of democracy, as she expressed sorrow over their departure.
However, she said PPP's decision to get their member elected as the Opposition leader in Senate was against the PDM's September 20 Charter — as they got support from treasury benches, and ANP backed them.
However, Aurangzeb reminded that the PDM had decided the Opposition leader would be from PML-N.
"If Gilani would have come back to PDM after his loss as Senate chairman …. then Nawaz Sharif would not have turned down his request to become the Opposition leader."