Rep. John Peterson (R), a six-term Member from northern Pennsylvania, will announce today that he is retiring. A Republican source cited health problems in his family as the reason why Peterson, 69, has decided to retire at the end of this term.

Peterson has easily won all of his general election campaigns with at least 60 percent of the vote. The district is considered safe for Republicans and no one but Peterson has filed for the seat with the Federal Elections Commission, though the state filing deadline is not until Feb. 12.

The most often-mentioned candidate for the seat is state Sen. Jake Corman (R), who represents Centre County. Corman is close to former Sen. Rick Santorum (R-Pa.), who was Corman’s father’s chief of staff in the Pennsylvania Senate.

“It really is his seat if he wants it,” said one Republican operative in the state.

The 5th district is the largest in size and most rural district in Pennsylvania, sprawling across the central northern third of the state. The population center is in Centre County, home of the Pennsylvania State University main campus.

Two other prominent Pennsylvania politicians, state Senate President Pro Tem and known Peterson adversary Joe Scarnati (R) and House Minority Leader Sam Smith (R), also represent part of the district. However state Republicans say it’s doubtful either would be interested in leaving their top posts to be a freshman legislator in Washington, D.C.

Pennsylvania Republican Northwest Caucus Chairman Ash Khare said that other than Corman, there is no consensus about anyone who might run for this seat with about six weeks left until the filing deadline.

Corman was unavailable for comment Thursday morning, but sources close to him told the online news outlet CapitolWire that they expect him to run for the seat. However the insider newsletter also reported Corman has three children younger than age 6, which might prevent him from running for the widespread 17-county district.

What’s more, Pennsylvania is due to lose a House seat to reapportionment in 2012. The 5th district might be a target for redrawing or elimination, though its already large size might save the seat. However this means whoever takes the seat in 2008 might have to give it up in 2012, depending on how the Congressional map is redrawn.

“Jake may have aspirations on a statewide thing down the road, so he may not want to run at this time,” said Khare, who also added that he would support Corman if he were to run.