Hastert said he did so on the advice of attorneys with the aim that a special primary election to replace him could be held on Feb. 5---the same day as the state's regular primary election, which will decide nominees for Hastert's long-term replacement as well.

Hastert said he wanted to avoid the extra costs of a special primary election by county election officials in the 14th Congressional District, which runs from western DuPage County to nearly the Iowa border. Still, those counties are likely to face extra costs for holding a special general election in late spring to fill the remainder of Hastert's term.

The former speaker said he also decided to step down now because his interests in developing new national energy policies was being sidetracked in the Democratic-controlled Congress, which is focused on the presidential election campaign.

"I wanted to get some energy policy done, but everything is being done behind closed doors on a partisan basis," Hastert told the Tribune. "You know, it seems to get tougher as we move into a presidential election year, and so I figured it was time for me to go out and live the rest of my life."

It's up to Democratic Gov. Rod Blagojevich to set the date of the special primary and general elections.

Dan White, executive director of the State Board of Elections, said he had yet to receive notice of Hastert's resignation.

White did, however, outline the process for replacing a congressman who resigns mid-term: the governor calls for an election within 120 days of the vacancy. White said his reading of the law is that a primary and general election would have to take place within the 120-day period.

Local officials would need to see how quickly that could be done given they would have to given proper notice of elections, White said.

The board acts mostly in a ministerial role, receiving the filing, but the duty and responsibility of running the elections would fall to the various local officials in his district, White said.

In his farewell speech, Hastert told his House colleagues earlier this month that he would step down from his seat before year's end.

Hastert said he had no immediate career plans, but said he expects to devote time to the creation of the Hastert Center for Economics, Government and Public Policy at Wheaton College, his alma mater. The school also will house a special library collection of his congressional papers.

Hastert, the longest serving GOP House speaker, said he had not explored job opportunities because of the potential for conflicts of interest while still a member of Congress.

"I'm going to talk to some folks. I may serve on some boards. I really don't know," Hastert said. But, he said, he had no plans to eventually lobby his former colleagues after what he said was a two-year ban on such activities by ex-House members.

Hastert also said he has not made a decision on whether to make an endorsement of a potential successor among the Republican field. The former speaker has not been on good terms with one contender, state Sen. Chris Lauzen of Aurora, who earned Hastert's enmity by polling a potential congressional run in 2005 while Hastert was still speaker.

"If I do, it will be later on in December," said Hastert, who previously backed another of his potential successors, Jim Oberweis, in a failed U.S. Senate bid.