SPRINGFIELD - Ameren Corp. officials estimated Thursday that some homeowners' monthly power bills could be about $40 more expensive than last year when air conditioners start running this summer.

Estimates were based on homeowners using 1,500 kilowatts a month, but individual use will vary significantly, depending on how hard they work their air conditioners or other appliances, said Ameren spokesman Leigh Morris.

The estimated monthly increases over summer 2006 bills are broken down this way:

- AmerenCIPS: $16.30

- AmerenIP: $27 AmerenIP: $27.70

- AmerenCILCO: $37.90

At the beginning of this year, Ameren's Illinois utilities were allowed to raise their rates for the first time in more than a decade.

"No one likes to pay more for any product or service, but the rising costs of electricity have made higher rates a necessity," said Stan Ogden, Ameren Illinois director of customer service.

But the high power bills have had lawmakers and other Springfield officials searching for an answer all spring. In debates on the topic, some said they hoped higher summer bills in Northern Illinois would force the state's Chicago Democratic leadership to take action.

But state Sen. Dan Rutherford, R-Chenoa, doesn't think that's likely.

"I can't imagine how it could be much more intense than this," Rutherford said.

A Commonwealth Edison spokeswoman said most homeowners would pay about $20 more a month this year if they use 1,500 kilowatt-hours. But if the house is heated with electricity, they'd pay about $20 less this year.

State Rep. Mike Bost, R-Murphysboro, said that because lawmakers are scheduled to adjourn by the end of the month, most people won't have turned their air conditioners on yet.

"By that time, we're out of session," he said.

But a group of lawmakers have refused to vote for a budget, a move that would keep them in Springfield until action is taken to lower customers' electric bills.

Mike Riopell can be reached at mike.riopell@lee.net or 789-0865.