Informal results from the vote showed that Mr. Sadr’s Sairoon alliance, favored by many working-class and leftist voters, had won 54 of 329 seats in Parliament. Fatah, the bloc of popular Shiite militia figures who earned respect for their defense of the nation against the Islamic State, placed second with 47 seats. Prime Minister Haider al-Abadi’s Nasr bloc came in third with 42 seats.

The results, however, have not been formally ratified, as the country has waited for the electoral commission to investigate allegations of isolated cases of fraud and reports of malfunctions in new electronic ballot machines. In the interim, envoys from foreign powers, including the United States, have met with the presumed winners and congratulated Iraq for what many described as a democratic success.

The election commission said on Thursday that it would appeal Parliament’s demand for a manual recount. The panel has denied that there were widespread irregularities in the vote.

It is unclear how the manual recount of ballots would affect the seat totals, but it would delay the formation of a new government for many more weeks — as well as cement the view that the political process is mired in corruption.

The election drew a historically low voter turnout of 45 percent, reflecting widespread disgust among Iraqis with their political leaders. That view has spread since the election, in part because of the way the electoral commission has handled complaints about the balloting.