The city clerk, Luis Pastoriza, refused to accept the petitions past the deadline.
"We're going into court," said Walker, who said he would prove that there was "skulduggery" involved in the decision by the clerk to rule him too late to file.
Walker said he and his running mates in the nonpartisan election had deliberately showed up last at the clerk's office as part of his "strategy."
"We know we got there at 3:59 p.m. That was by design," Walker said. "We intended to be the last ones in. That was part of the plan. But we did not contemplate the shenanigans."
Mr. Collins said, "Is this any different than the Gore-Bush situation in Florida? The chads and voting ballots? In Florida they wouldn't accept the votes. Here they won't accept our petitions . . . ."
Walker and Collins said their watches and Garrison's indicated they were on time. But the clerk's office clock showed they were late.
"The clerk said he was using City Hall clocks," Walker said. "Both of my opponents have offices in City Hall. Naturally that gives them an unfair advantage in time."
Pastoriza denies any shenanigans.
"I don't have a problem with him taking exception to what I've done," Pastoriza said. "I only enforce the law. I think I did my job. I have to be objective."
Walker said Pastoriza was "an honorable man. But I can't say that about the elected officials. I think there may have been undue pressure from supporters of Gilbert 'Whip' Wilson, who were in the office at the time."
He said there were six Wilson supporters in the office at the time.
Pastoriza denied being influenced by anyone. "If I didn't do what I did, I would have opened a Pandora's box, a floodgate of problems."
Walker was also the first to announce his slate, first to unveil an elaborate plan for the city's recovery, and first to establish a campaign headquarters, hung with red-white-and-blue banners, next to City Hall, mere steps away from the clerk's office.
Walker, a former assistant business administrator in Camden, who was fired after a falling out with Milan, has been pegged as a wild card candidate in the race. The other announced candidates are interim Mayor Gwendolyn Faison, 76, and Councilman Gilbert "Whip" Wilson, 53.
The speculation among some local political observers on Thursday was, with Walker not on the ballot for the May 8 election, a runoff would be avoided. Barring a strong write-in candidate, either Wilson or Faison could easily gain the half-plus-one majority required to win election.
Faison, a former City Council president, became mayor last December after Milan was convicted of federal corruption and sentenced to prison. Wilson, a former Camden police officer, has been on Council since July 1997.
Dwight Ott's e-mail address is firstname.lastname@example.org.