Ney has represented Ohio's 18th District since 1994 and won his May primary but withdrew from the race in August saying that the investigation was taking a heavy toll on his family.
Joy Padgett, an Ohio state senator backed by Ney, House Majority Leader John Boehner, R-Ohio, and the Republican Party, easily won a special primary held on Thursday to replace Ney on the November ballot.
In the Justice Department's investigation into the congressional scandal, Ney will plead guilty to federal corruption charges that he made false statements, conspired to commit "wire and mail fraud," and violated federal lobbying laws.
Ney apologized for his actions saying that "he takes full responsibility" and that he recently realized that "a dependence on alcohol has been a problem for me."
On Thursday, Ney checked himself into a rehabilitation clinic for alcoholism.
"I have made serious mistakes and am sorry for them. I am very sorry for the pain I have caused to my family, my constituents in Ohio and my colleagues," Ney said in a statement.
Ney faces up to 10 years in prison. He is the first congressman to plead guilty in the federal probe.
The investigation made Ney's seat in a Republican-leaning district a target for Democrats eager to use ethics scandals in Washington to their advantage. Padgett will face Democrat Zack Space, the Dover law director who launched an aggressive advertising campaign focusing on cleaning up corruption in Washington and Ohio. He will try to use Ney and ethics scandals in Ohio against Padgett. In an interview with CQpolitics.com, Space labeled Padgett as "Bob Ney's handpicked successor."
Padgett has just 53 days before the general election to distance herself from Ney and unpopular Ohio Republican Gov. Bob Taft who was found guilty of ethics charges.
Padgett won 63 percent of the vote against four little-known candidates in the special primary: James Brodbelt Harris, a financial analyst who lost to Ney in the May primary, Ralph A. Applegate, a frequent candidate who lost to Zack Space in the Democratic primary, Holmes County Commissioner Ray L. Feikert, and retired newspaper publisher Jerry Firman.
The candidates had less than a month to campaign and election officials said that voter turnout was low. According to the Times Reporter in New Philadelphia, some voters were unaware there was a special election. "I don't know who's in the race or where any of them stand," said Tess Sexton, a Republican in McArther as quoted in the Times Reporter.
Padgett served six years in Ohio's House and was elected to the state Senate in 2004, defeating Democrat Terry Anderson, a journalist who was held hostage in Lebanon.
After Ney's resignation, Democrats tried to prevent Padgett from entering the race, citing Ohio's "sore loser" law that bans candidates who lose in a primary from competing in another primary within a year. Padgett and state Attorney General Jim Petro lost to Ohio Secretary of State Ken Blackwell for the Republican nomination for governor. Petro cleared Padgett to run and Democrats did not formally file a complaint.