The state takeover of Pennsylvania's financially troubled capital city received a fresh challenge Thursday, as three Harrisburg residents filed a federal lawsuit calling it an unconstitutional violation of their rights and asking for it to be stopped.

The suit names Gov. Tom Corbett, who signed a law on Oct. 20 enabling an unprecedented takeover of Harrisburg, and the Corbett appointee who, if confirmed, would have broad authority to force the city to pay down a massive debt tied to its trash incinerator.

The lawsuit was filed by a former mayoral candidate, a firefighters' union president and a religious leader. It alleges that the law and the state's takeover violate the plaintiffs' constitutional rights to due process and equal protection.

A Corbett administration spokeswoman said she had not seen the lawsuit and could not immediately comment.

The suit is the latest twist in a battle over who will end up footing the $300 million incinerator debt.

The first attempt to stop the takeover failed last week when a federal bankruptcy judge threw out a petition by a divided City Council to get federal bankruptcy protection for Harrisburg. The judge said the city had been legally barred by a separate state law — signed June 30 by Corbett — from seeking bankruptcy protection and, in any case, had no authority to go over the mayor's head to file it.