It's pretty exciting and quite surprising that Tuesday's so-called Chesapeake Primary - which includes Virginia and the District of Columbia along with Maryland - could affect the outcome of the Democratic presidential nomination contest between Sen. Hillary Rodham Clinton and Sen. Barack Obama. Usually the nomination process for both parties is effectively over by the time Maryland's spot on the calendar arrives.

While it's tempting to write more about the choice between Senators Obama and Clinton, there is another Democratic primary in the state of lesser national consequence but far greater contrast: that between 4th District incumbent Rep. Albert R. Wynn and his second-time-around challenger, Donna Edwards.

To put it bluntly, Mr. Wynn, an eight-term congressman, is an embarrassment to his Prince George's County-based district, the state and the Democratic Party. And his past - his machine-style bossism, dirty politics and political bullying - is catching up with him.

In 2006, he sent out a flier implying he had won endorsements from some unions that hadn't endorsed him.

That same year, two of his supporters physically harassed one of Ms. Edwards' campaign volunteers.

This cycle, he filmed a political ad fashioned to look like a news reporter had caught him randomly on the street for an interview, when in fact the ad was staged by his campaign.

And then last week, Mr. Wynn, who is a lawyer, filed a completely bogus Federal Election Commission complaint that charges Ms. Edwards with violating election law. As The Sun has reported, the complaint is so slapdash that it doesn't even bother to cite specific election law provisions.

All of these electoral shenanigans are designed to mask Mr. Wynn's real problem: his voting record, which reflects contempt for voters in his district and the opinions of many Marylanders.

He voted in October 2002 for President Bush's Iraq war resolution. In 2004, Mr. Wynn voted for Vice President Dick Cheney's energy proposal, even though every other member of Maryland's House delegation, including both Republicans, voted nay.

He has accepted more than $200,000 in campaign contributions from banks and lending institutions, and, not surprisingly, voted in 2005 for a Bush administration-backed bankruptcy "reform" bill with punitive provisions for working-class borrowers.

To be fair, the 4th District is not a typical majority-minority district: It is one of the most affluent such districts in the nation, with a median income much higher than the state's other majority-minority district, represented by fellow Congressional Black Caucus member Rep. Elijah E. Cummings.

All caucus members should not be expected to vote in lockstep, of course. But on key issues, Mr. Wynn has exhibited greater concern for the agenda of Prince George in the White House than Prince George's in the people's House.

One must wonder if such votes have something to do with the fact that before 2006, he benefited from an unusual degree of electoral comfort. Safe in the knowledge that the overwhelming Democratic 4th District was noncompetitive in any general election, Mr. Wynn was licensed to vote with an expectation of impunity.

Then along came Ms. Edwards. The former director of the ARCA Foundation, an organization that works for social justice issues, she has worked diligently to combat domestic violence and promote a living wage - and she dared to challenge Mr. Wynn in the 2006 Democratic primary.

Despite scarce resources and almost no initial name recognition, she parlayed a grass-roots movement and the endorsement of The Washington Post into a competitive challenge that came up a bit shy.

Ms. Edwards lost, but by only about 3 percentage points - a margin that is rare in general elections for Congress and even rarer in primaries when an incumbent is seeking re-election.

To his credit, Mr. Wynn had selflessly agreed to assume a bit more electoral risk this decade by accepting in 2001 a gerrymandering proposal by then-Gov. Parris N. Glendening that swapped some Democratic precincts from Mr. Wynn's district with the neighboring, Montgomery-based 8th District as a way to improve his party's hopes of unseating Republican Rep. Constance A. Morella in 2002. (The move worked: Then-state Sen. Chris Van Hollen defeated Ms. Morella.)

But, in whichever county his constituents reside, Mr. Wynn too often places his political power over the voters' interests. For that reason alone, he ought to be handed an electoral pink slip on Tuesday.

Thomas F. Schaller teaches political science at UMBC. His column usually appears on alternate Wednesdays in The Sun. His e-mail is schaller67@gmail.com.