The city's political landscape is likely headed for chaos because of Mayor Michael Bloomberg’s expected announcement that he will ask the City Council to change the term limits law to run a third time.

"In terms of keeping people in power by changing the rules halfway through the game, never seen anything like this," said political consultant Norman Adler.

The move would have implications beyond Bloomberg.

It means candidates who've been raising millions of dollars to replace him will have to rethink whether they should go forward with their plans, to take on a popular billionaire incumbent.

Besides the mayor, revising the term limits law could mean the two other citywide officials, comptroller and public advocate, would be able to seek a third term, as would 34 council members.

One complication for some will be the city's public financing system.

"Lots of candidates will be affected,” said Campaign Finance Board executive director Amy Loprest. “There are some things in the law that are relatively clear. There are very clear contribution limits for candidates, but how to treat the spending will be more problematic. So the board is looking into ways to deal with that."

For example, council members running for a citywide seat can spend more than if they are up for re-election. If they decide to run again for their jobs in the council, some may have already reached the spending limit.

Angry voters are another pitfall. In two referendums, New Yorkers upheld the term limits law.

Good government groups argue it's wrong for the council to overturn the will of the voters and may fight back.

"We have many options on the table,” said Dick Dadey, Citizens Union. “One of them, of course, is legal action, which is something we are looking at. The other options are to organize a citizen’s petition to put a ballot during a special election sometime next year and have voters express a preference on this question."

Whatever happens, New York could be in for an unprecedented election next year.