What in the world is going on in the U.S. Senate?

On Monday, August 27, news services broke the story that Sen. Larry Craig, R-Idaho, pleaded guilty in early August to lewd conduct in an airport restroom. According to the arresting officer, on June 11, Craig stood in front of the officer's stall and "fidget[ed]" with his fingers. He then took the stall next to the officer, tapped his right foot, signaling that he was interested in lewd conduct, and blocked the front view of his stall using his roller suitcase. He then edged his foot into the officer's stall and touched the officer's foot. After Craig signaled yet again that he wanted to engage in lewd conduct by swiping his fingers beneath the stall divider, the officer promptly arrested him.

Craig pleaded guilty to charges of lewd conduct on August 8. This week, Craig denied the charges. "At the time of this incident, I complained to the police that they were misconstruing my actions," Craig stated. "I was not involved in any inappropriate conduct."

Right. And neither was George Michael.

Craig is hardly the only member of the Senate with a propensity for dropping his pants at inopportune moments. Sen. David Vitter, R-La., admitted earlier this year that his phone number was on the list of a D.C. prostitution service. Sen. Ted Kennedy, D-Mass., even leaving aside the Chappaquiddick incident, is famously promiscuous -- so much so that he once dubbed himself "Tyrannosaurus Sex" and joked that his nickname was the "floating screw." Sen. Daniel Inouye, D-Hawaii, has allegedly sexually harassed or abused at least 10 women. Sen. Maria Cantwell, D-Wash., reportedly engaged in a sexual affair with an engaged lobbyist, Ron Dotzauer, then gave him a personal loan to help him with his subsequent divorce and threw cash his way.

And of course, allegations of corruption aren't limited to those of the sexual variety. Senate Majority Leader Harry Reid, D-Nev., has been mired in financial dirty dealing for years. Sen. Hillary Clinton, D-N.Y., likely bought hundreds of votes in a Hasidic New York neighborhood during her 2000 senatorial run by persuading her husband to commute criminal sentences for several New Square residents. Sen. Bill Frist, R-Tenn., has been investigated for supposed insider trading.

The simple explanation for the Senate's corruption infection would be a standby aphorism: "power corrupts." But that's too easy. Our Founding Fathers recognized that a body of glory-seeking power players would take advantage of their situation. To that end, they strictly circumscribed the power of the Senate and placed senators under the control of their state legislatures.

Today, however, those controls have been jettisoned. Senators are directly elected, meaning they must find some payoff for voters. That payoff comes in the form of earmarking. As long as the payoffs keep coming, voters keep voting.

This is especially true for Democratic politicians, whose voters are often dependent on the tax dollars their senators bring home. When Republicans engage in sex scandals or clear-cut corruption, they resign or face the wrath of their constituents -- ask Mark Foley, Jack Ryan, Bob Livingston, Bob Packwood, Ed Schrock and Don Sherwood, among others. When Democrats engage in sex scandals or clear-cut corruption, they retain their seats as long as they keep the cash flowing -- just ask Gerry Studds (re-elected six times after having sex with a male congressional page), Barney Frank (re-elected eight times after his gay lover ran a male escort ring out of his apartment), Mel Reynolds (re-elected despite facing an indictment for sexual assault and criminal sexual abuse of a 16-year-old campaign worker), Sen. Charles Robb (re-elected despite credible sex scandal allegations) and Gus Savage (re-elected despite fondling a Peace Corps volunteer).

Larry Craig will almost certainly resign his Senate seat. But Craig is a symptom of a deeper problem plaguing our politics. Until voters insist on honesty rather than payoffs, corruption will remain endemic to the halls of power.