Mark Green tried to assert himself Monday as the Democratic mayoral nominee, but Fernando Ferrer refused to quit the race.
Four days after the primary runoff election, the outcome remained uncertain because of errors discovered in the unofficial results provided to the media.
An audit of the votes completed Monday evening by The Associated Press showed Green's unofficial lead had shrunk from about 30,000 to about 19,000.
The vote totals were 391,297, or 51 percent, for Green and 372,249, or 49 percent, for Ferrer, the Bronx borough president. The total vote had diminished from about 805,000 to about 763,000.
The tightening race prompted Ferrer, who had conceded Thursday, to backtrack, saying that while he was committed to supporting the Democratic nominee, "We don't know who that nominee is."
But Green, the city's public advocate, insisted Monday he was "looking forward to a formal certification of what is unofficially known now, that I'm the Democratic nominee for mayor."
The winner faces Republican Michael Bloomberg in November.
Thousands of votes were mistakenly entered twice in the unofficial count. Those results are gathered and entered by the Police Department, which transmits them to the AP. The AP tabulates the numbers and distributes them to newspapers and broadcasters.
On Friday, the AP began an audit of the results and began to detect errors when it compared the paper canvass sheets from each election district with the numbers that had been entered Thursday night.
There were more than 50,000 paper and absentee ballots as well but many are subject to challenge, and since they tend to reflect the machine vote they are unlikely to affect the outcome.
The Board of Elections has not yet begun its official tally of the votes. Those results are due Oct. 23.
Many Democrats, especially blacks and Hispanics, viewed the results with suspicion.
"We Democrats have a very serious problem," said Rep. Charles Rangel, a black congressman who had endorsed Ferrer before Thursday's runoff and has called for an investigation of the results.
Rangel and the Rev. Al Sharpton said Monday that the consolidation of some election districts -- the ones where results were counted twice -- may have violated federal election rules.
Sharpton said the consolidation by law should have been approved by the federal government beforehand. He said he planned to file suit by Wednesday calling for a new runoff or a federal review. 
Copyright 2001 Associated Press