The party of Pakistani opposition leader Nawaz Sharif says it will contest general elections due to be held in January.
Mr Sharif had threatened to boycott the election
The PML-N decision came after it failed to agree a boycott with Mr Sharif's opposition rival, Benazir Bhutto.
The two sides complained the poll would not be fair, given a state of emergency imposed by President Pervez Musharraf.
President Musharraf said on Sunday he would lift the emergency on 15 December, a day earlier than planned.
In an interview with US broadcaster CNN, he confirmed remarks by his attorney general that "the emergency will be finished on the 15th".
Emergency rule was declared more than a month ago. President Musharraf has since quit his post as army chief.
The decision that Mr Sharif's party would stand in the parliamentary elections came after 33 opposition groups, including Ms Bhutto's Pakistan People's Party, met in Lahore but failed to reach a joint position.
"Since we could not reach any agreement with the People's Party and they are contesting polls, we cannot leave the field open," said Ahsan Iqbal, spokesman for the PML-N.
Ms Bhutto says a boycott would benefit the president
He told the BBC that the party's manifesto would be a single demand, the restoration of judges deposed by President Musharraf in November to fend off possible challenges to his re-election as president.
Mr Sharif and Ms Bhutto, who are both former prime ministers, had differed on this issue. She maintains that the new parliament should decide whether to reinstate the judges.
Ms Bhutto has said she will contest the elections "under protest", but reserves the right to challenge the results if she feels the vote is not fair.
She has argued that to boycott the polls would leave the field open for supporters of President Musharraf.
The BBC's Roland Buerk in Islamabad says a joint boycott would have deprived the election of credibility, but the two leaders' suspicion of each other seems to have outweighed their distrust of the president.
Mr Sharif is himself barred from standing in the election because of criminal convictions against him.
These date back to 1999, shortly before he was deposed by the then General Musharraf in a bloodless coup.
He was found guilty of hijacking and terrorism after ordering that a plane carrying Gen Musharraf back to Pakistan be stopped from landing.
He and Ms Bhutto have both returned from exile in recent months.