Sunni groups have felt particularly targeted by the ban
Iraq's electoral commission has said it will delay the start of campaigning for next month's parliamentary elections.
The move follows a court decision to overturn a ban on candidates barred because of alleged affiliations with Saddam Hussein's outlawed Baath party.
An appeals panel ruled the ban should be overturned, but the government wants it to remain in place.
The political campaign, due to start on Sunday, will now begin next Friday to allow time for the row to be resolved.
"The start of election campaigning has been postponed from 7 February to 12 February to give time to the federal court to look into our inquiry," Hamdiya al-Husseini, an official with the Independent High Electoral Commission said.
The delay will allow time for an emergency parliamentary debate, to be held on Sunday, on the court ruling, which the government has called "illegal and unconstitutional".
The election is regarded as a crucial test for Iraq's national reconciliation process ahead of a planned US military withdrawal.
On Wednesday, the appeals panel ruling overturned a ban on some 500 politicians from running for public office.
The BBC's Gabriel Gatehouse in Baghdad says that although the list of names straddles the sectarian divide, it is Sunni groups who have felt most targeted by the exclusions, and whose voices of protest have been heard loudest.
Baathism is a form of secular Arab nationalism and was the ideology espoused by Saddam Hussein when he came to power.
Although a minority, Sunni Muslims were dominant under Saddam Hussein's rule but have since complained of being marginalised under the post-Saddam Shia-led government.
The ruling would allow the candidates to stand for election, and be subject to investigation only after the polls.
US officials had voiced concerns about the ban, fearing that it could inflame sectarian tensions and undermine confidence in the electoral process.
There are still more than a 100,000 American troops in Iraq and the Pentagon's exit strategy depends in large part on a peaceful and credible election, our correspondent says.