There are three special elections coming up for the House of Representatives in conservative districts in the Deep South: in Louisiana's first district (to replace Bobby Jindal, who became governor), Louisiana's sixth district (to replace Richard Baker, who resigned to become a hedge-fund lobbyist), and Mississippi's first district (to replace Roger Wicker, who took over Trent Lott's Senate seat). Polling indicates that Democrats have an off-chance of picking up two of these seats (Louisiana-6 and Mississippi-1). Via Daily Kos, though, one interesting point to note is that the ballot in the Mississippi race doesn't show the candidates' party membership (see ballot at right). Travis Childers is the Democratic nominee in the race; Greg Davis is the Republican nominee.
This probably benefits Childers. Since the district is fairly solidly Republican, with a Cook Partisan Voting Index of R+10, the Democrat benefits if the salience of party identification is lower. (One wonders, indeed, if this ballot was designed deliberately by a partisan Democrat.) From a normative standpoint, though, this is incredibly problematic. Given the rules governing the operation of the House of Representatives, for better or for worse, in any House race partisanship is the single most important factor to consider if your goal is to move national policy in a direction that aligns with your preferences. To deprive voters of that information on the ballot is a major impediment to the functioning of the democratic process.
The common response is that by omitting party affiliation, in effect you impose a political literacy test on voters: In order for your vote to have maximum ideological efficacy, you must have paid enough attention to the campaign to know which candidate is a Republican and which is a Democrat. I think this asks too much of voters, though, at least in the context of House races. It's perfectly rational to say: "I'm busy and I have no interest in following the details of this political campaign. I know my preferences align largely with the platform of the (Republican/Democratic) party, and since the House functions in a manner such that the majority party sets the agenda, I'm simply going to vote along party lines." Of course it would be nice if voters engaged in a more nuanced calculation than this, but it's hard to make the case that it should be a de facto requirement that they do so.
This matters slightly less during a special election, where the vast majority of people informed and motivated enough to actually go vote will probably know the candidates' party affiliations anyway. And the nonpartisan ballot--a major reform pushed by early-twentieth-century progressives to dilute the influence of party bosses--may have slightly more to recommend it in a municipal context. But denying voters the ability to cast a party-line vote for a party-line institution, during an era in which partisanship and ideology are closely intertwined, does a major disservice to democracy.