CHICAGO (Legal Newsline) - Illinois Attorney General Lisa Madigan asked the Federal Energy Regulatory Commission on Tuesday to examine how a proposed merger between Exelon and Constellation might affect the state's power markets.

Exelon Corp. proposed the takeover of Constellation Energy Group Inc. Madigan asked the agency in her filing to reject the $8 billion agreement between Exelon and Constellation, Crain's reports.

The company still is reviewing Madigan's filing and said it has alleviated market-power apprehension.

"We firmly believe that we have satisfied the commission's market-concentration tests and fully mitigated any market-power concerns," an Exelon spokesman said, according to Bloomberg.

Exelon's territory covers a large portion of Northern Illinois. The deal has already drawn opposition in Maryland, where Constellation is based. Maryland's ratepayer advocate objected to the proposed buyout in July, telling federal regulators that the combined company would have too much control of electricity prices on the grid.

"If market power can be exercised, it would have an effect on wholesale prices and transmission rates, and it's not a good thing for Maryland ratepayers," Paula Carmody, the people's counsel, said, according to the Baltimore Sun. "The natural expectation is that this can lead to an increase in prices."

Madigan filed a protest a similar protest in July against the merger.