Former Pakistani Prime Minister Benazir Bhutto has said that talks on a power-sharing deal with President Pervez Musharraf are "totally stalled".
Ms Bhutto says she plans to return to Pakistan to fight elections
Speaking in London, she said reports that corruption charges against her had been dropped were "disinformation".
She also said she expected her party to join a boycott of parliament.
The self-exiled Ms Bhutto has pledged to return to Pakistan on 18 October. President Musharraf looks certain to be elected for a new term on Saturday.
Ms Bhutto, who denies allegations of corruption, has lived abroad since well before Gen Musharraf seized power in a coup in 1999.
She has been one of his sternest critics, but is now a possible future ally.
A deal between the pair has appeared close a number of times during negotiations which have gone on for months.
The BBC's M Ilyas Khan in Karachi says Ms Bhutto may be trying to exert pressure on the president to make more concessions, which are very hard for him to grant.
Ms Bhutto was speaking to reporters at a meeting of her Pakistan People's Party (PPP) central executive in London.
06 Oct: Presidential vote due to be held
18 Oct: Date ex-PM Benazir Bhutto has set for her homecoming
15 Nov: Parliamentary term ends and general election must be held
Asked if her MPs would join other opposition parties in resigning en masse from Pakistan's assemblies ahead of Saturday's election, she said "most probably".
"We don't want to resign. But certainly we're being pushed into taking the step."
She said a final decision would be made either later on Wednesday or on Thursday.
"I think that the resignation of the Pakistan People's Party MPs will be a severe blow to the legitimacy of the presidential election."
Earlier, she said reports that she no longer faced corruption charges in Pakistan were "totally wrong".
"This is just a typical disinformation campaign by the present regime," she said.
The BBC's Barbara Plett in Islamabad says the government's announcement that it was close to finalising an agreement to drop corruption cases against Ms Bhutto may have been aimed at dissuading her from joining the boycott being observed by other opposition parties.
Pakistan has faced growing political and security instability in recent months.
Gen Musharraf's election plans are illegal, critics say
The PPP is the biggest party in Pakistan. Observers say Gen Musharraf wants a power-sharing agreement with the PPP to give him more popular support.
But Ms Bhutto has been insisting that the president gives up his power to sack the prime minister.
She also wants the repeal of a law banning anyone from being prime minister for more that two terms. She and political rival Nawaz Sharif have both been prime minister twice.
He returned to Pakistan in August but was promptly deported to Saudi Arabia.
Ms Bhutto, who faces possible arrest in Pakistan because of the corruption cases, says she will return to lead her party in general elections due by mid-January.
Pakistan's president is elected indirectly by parliament and the four provincial assemblies. Gen Musharraf's supporters say they are confident he has the support to win another term.
But it is thought he will need help in parliament, most probably from the PPP, after the general elections in which the ruling party is expected to fare badly.
Opposition resignations aimed at undermining the credibility of the ballot make victory for the president even more certain, observers say.
Meanwhile, judges in the Supreme Court are continuing to hear petitions challenging the president's right to stand for election while still army chief.