One of the fundamental differences between Republicans and Democrats usually becomes evident when there's a scandal. When Republicans are caught misbehaving, they normally resign. Recall Rep. Livingston who immediately called it quits over a sex scandal. By contrast, Bill Clinton, with the solid support of his party, was clinging to power even though he had committed perjury in connection with a sex scandal. If such Republicans aren't inclined to resign, the odds are good that either their caucus or their constituents will promptly toss them overboard.
Interesting theory. Let's test it, shall we?
In the last congress, there were 18 Senators and Congressmen who were under federal investigation. 14 were Republicans. Of those, four resigned while in office. For two (Bob Ney and Duke Cunningham), it occurred roughly concurrent with a criminal conviction, so no props. Tom DeLay did resign prior to any criminal conviction, but only after trying to seize even more power for himself, and certainly (as his new blog shows with no sense of shame or remorse. Still, we will count Rep. DeLay as having resigned in the face of scandal. That's one. And Mark Foley also resigned pretty much as the scandal broke, so that's two.
Of the 10 remaining Republicans, two (Sen. Bill Frist and Rep. Jim Kolbe) had announced their retirement at the end of the term, but did not resign (and were not popularly thought of as having been forced into retirement due to scandal). Two more (Sen. Conrad Burns and Rep. Curt Weldon) ran for re-election but were defeated, while Katherine Harris became the GOP's Senate candidate and lost her seat that way. The five remaining GOPers are still in Congress. They are Reps. Rick Renzi, Jerry Lewis, and John Doolittle, and Senators Ted Stevens and Arlen Specter. Lewis was the chair of the House Appropriations Committee, Doolittle was the House Republican Conference Secretary, Specter was the Senate Judiciary Committee Chair, and Stevens was the Senate Appropriations Committee Chair (and Senate pro tempore). So these aren't small fish. With the exception of Senator Specter (where it is happening for reasons wholly unrelated to corruption), I am aware of no calls for any of these people to relinquish their committee assignment.
Of course, this list does not include politicians whose scandals have not yet prompted a federal investigation (like Dennis Hastert). Still, even with the limited data that we have, some interesting themes develop. On the one hand, 9 of the 14 officials under investigation are no longer in Congress. So that's a point in the GOPs favor. On the other hand, only four of those nine left voluntarily, and only two of those left because of scandal. So that's a point against. There also has been no discussion of action against those Congressmen who have refused to relinquish their seats, as there has been in the case of three of the four Democrats under investigation (Reps. Jane Harman, Alan Mollohan, and William Jefferson; the fourth is Sen. Bob Menendez). At least one corrupt politician was given the opportunity to be promoted (Harris in Florida). Ultimately, only 2 of 14 GOP elected officials under investigation left office due to scandal, or 14%. That isn't a great margin, and certainly not enough to warrant Mr. Mirengoff's claim.
Though none of the four investigated Democrats has left office, there have been significant actions taken against them. Harman was denied a coveted chair of the Intelligence Committee, in part because she was seen as too close to Israel (which is related to the federal investigation into her connections to AIPAC). Jefferson, of course, was stripped of his committee assignment, and many prominent Democratic voices have urged that he be denied reseating come 2007. Compare that Republicans, which tried to specifically protect Tom DeLay from punishment in the event he was indicted. Moreover, since there are 3.5x as many Republicans as Democrats under investigation in the first place, and Republicans only resign due to scandal at a rate of 1 in 7, there are simply fewer Democrats available to do the "right thing", because fewer are doing the wrong thing in the first place.
In the end, the most even-handed assessment I can make is that: a) there are more corrupt Republicans than Democrats; b) when caught, individual Republicans may be marginally more likely to resign than Democrats who are caught; and c) Democrats are more likely to punish their non-resigning corrupt politicians than are Republicans. Any corruption, of course, is too much corruption, and both parties are not nearly committed enough to rooting it out for my tastes. But to suggest that the GOP is more responsive to corruption in its midst is simply fanciful, and the data does not bear it out.
Urging once-a-day voting seems oddly appropriate now...