Sen. John Ensign is on the list of the top 10 ethics scandals of 2009 compiled by Citizens for Responsibility and Ethics in Washington, D.C.
CREW is a non-profit legal watchdog group formed to hold public officials accountable for their actions.
The group listed the Nevada Republican based on his conduct involving his affair with Cynthia Hampton, his campaign manager and wife of his then-administrative assistant Doug Hampton.
"First, by terminating Mr. and Ms. Hampton after the affair ended, Sen. Ensign may have engaged in sexual harassment," the CREW report states. "Second, the failure to disclose the $96,000 severance payment made to Ms. Hampton likely was a criminal violation of campaign finance law."
But the report says most damning is Ensign's efforts to help Doug Hampton become a lobbyist in violation of the one-year lobbying ban for senior staff.
Sen. Tom Coburn, R-Okla., was also criticized for helping Hampton violate the lobbying ban by meeting with Hampton's lobbying clients.
The authors of the report called on Ensign to resign "and save us all from more excruciating details about his reprehensible conduct." The report calls for an investigation of both Coburn and Ensign.
Ensign's office has repeatedly refused to comment on either the affair or allegations of wrongdoing in how the situation was handled.
Ensign wasn't the only sexual scandal on CREW's list. South Carolina Gov. Mark Sanford's affair with an Argentinean woman also made it. His state ethics commission is considering 37 charges involving travel and campaign finance violations.
In addition to Ensign and Sanford, the CREW list includes:
• Wall Street executives responsible for the financial meltdown awarded themselves $18.4 billion in bonuses even as the federal government authorized $700 billion to bail out financial institutions.
• The Securities and Exchange Commission's failure to catch Ponzi schemer Bernie Madoff despite six complaints beginning in 1992. The damage caused by Madoff's swindle is estimated at $65 billion.
• Supreme Court leaning toward gutting the mail fraud statute designed to fight public corruption.
• Federal Elections Commission for allowing numerous violations of federal campaign finance laws because the commission is deadlocked with three Republican and three Democratic appointees.
• Rep. Charles Rangel of New York for ethical violations including using congressional stationery to raise funds and not disclosing to the IRS $75,000 in income.
• The U.S. Senate for failing to follow the law requiring they identify themselves when placing a hold on legislation. The tactic is used by senators to anonymously block nominations and bills.
• Congressional indifference to the ongoing reports that some members have cozy relationships with the now-defunct PMA Group of lobbyists, which is being investigated for role in trading legislative earmarks for campaign contributions.
• Despite vows to "drain the swamp," not one member of Congress was publicly reprimanded or sanctioned by the House ethics committee this year. Meanwhile, a Gallup poll shows 55 percent of Americans believe the honesty and ethical standards of members of Congress are either low or very low.