INDIANAPOLIS — Indiana Republican Rep. Mark Souder announced Tuesday he would resign from Congress, effective Friday, because he had an affair with a staffer.

The eight-term congressman apologized for his actions but provided no details.

“I am so ashamed to have hurt the ones I love,” he said at a news conference in Fort Wayne. “I am sorry to have let so many friends down, people who have worked so hard for me.”

Souder’s decision could damage the Republicans’ chances of holding onto the GOP-leaning district in northeastern Indiana. Souder won a bruising Republican primary on May 4 with 48 percent of the vote and was to face the Democratic candidate who four years ago gave him the toughest challenge since he was first elected in 1994.

Souder, 59, said he would not be a candidate in the fall election. It will be up to Republican Gov. Mitch Daniels to decide whether to call a special election to fill the vacancy or wait until the November ballot.

“I sinned against God, my wife and my family by having a mutual relationship with a part-time member of my staff,” Souder said. “In the poisonous environment of Washington, D.C., any personal failing is seized upon and twisted for political gain. I am resigning rather than put my family through a painful drawn out process.”

Souder has been married to his wife, Diane, since 1974, according to the biography on his office website. They have three adult children and two grandchildren.

Souder won the Republican primary over car dealer Bob Thomas, who spent much of his own money on television commercials portraying Souder as a career politician who wasn’t a true fiscal conservative. Souder countered by emphasizing his A-plus marks from the National Rifle Association and 100 percent rating from the National Right to Life Committee.

Souder had been expected to face a stiff contest against Democrat Tom Hayhurst, a former Fort Wayne city councilman who got 46 percent of the vote against Souder in 2006. Nevertheless, the 3rd Congressional District has a strong Republican tilt; John McCain carried the district by more than 10 points in the 2008 presidential election.

One possible Republican replacement for Souder is state Sen. Marlin Stutzman of Howe, who finished second to former Sen. Dan Coats in this month’s GOP primary for the U.S. Senate.

Hayhurst said in statement that his thoughts and prayers were with Souder and his family.

“I’m not running for Congress to run against anyone, but I’m running because I think I can help change Washington and that will not change not matter who is in the race,” Hayhurst said.

Souder’s resignation continues a significant turnover among Indiana’s congressional delegation this year.

Democratic Sen. Evan Bayh announced in February he wouldn’t seek re-election, saying he had tired of Congress. Democratic Rep. Brad Ellsworth is leaving his southern Indiana seat to run for Bayh’s position.

Republican Rep. Steve Buyer said he January he wouldn’t seek a 10th term in the House after his wife was diagnosed with an incurable autoimmune disease.

from www.usatoday.com – There are news reports out today that Rep. Mark Souder, an Indiana Republican, will resign because of an affair with a female aide.

Our friend Sylvia A. Smith at the Fort Wayne Journal Gazette has a statement from Souder, who told her that he is resigning because he “sinned against God, my wife and my family by having a mutual relationship with a part-time member of my staff.”

“I am so ashamed to have hurt those I love,” Souder told the Journal Gazette in a written statement. “I am so sorry to have let so many friends down, people who have fought so hard for me.

Souder, who describes himself as an evangelical Christian, came to Congress in 1994 as part of the “Republican Revolution” led by Newt Gingrich. The congressman recently won a contested GOP primary, in which opponents criticized his support for the 2008 federal financial bailout and for his support for the “Cash for Clunkers” program.

Our Gannett Washington Bureau colleague Maureen Groppe says Souder, who is married with three children, is resigning so he doesn’t put his family through a painful process in Washington where “any personal failing is seized upon, often twisted, for political gain.”

Maureen writes that Souder, 59, had just survived a competitive primary but was expected to be re-elected in his heavily Republican district. The Democratic nominee is Tom Hayhurst, who got 46% of the vote against Souder in 2006.

Souder said that after leaving office Friday, he plans to focus on repairing his marriage, earning back the trust of his family and community, and “renewing my walk with my Lord.”

The 3rd Congressional District is centered in Fort Wayne and has traditionally been good to Republicans. John McCain won the presidential vote in the district in 2008, with 56%.

Souder would be the second member of Congress to resign this year amid a scandal. Rep. Eric Massa, D-N.Y., stepped down in March amid allegations of inappropriate behavior with a male staffer.

Updated at 11 a.m. ET: Our colleague Fredreka Schouten just talked with Michael Steel, a spokesman for House Minority Leader John Boehner, who would not say whether Boehner urged Souder to resign. But Steel said Boehner “has been perfectly clear that he will hold our members to the highest ethical standards.”

The two men spoke about the resignation Monday, Steel said — a day after Souder’s staff reached out to Boehner’s aides to inform them of the news.