Minnesota Representative Michele Bachmann's announcement yesterday that she won't seek another term is having an unexpected effect: Her fellow Republicans are rejoicing and Democrats are in despair.

Parties usually lament the retirement of incumbent lawmakers because their seats become harder to hold. Bachmann's perch, however, was a top Democratic target for takeover next year. She barely won re-election last time and now faces several ethics and campaign-finance investigations.

Her 2012 opponent, Democrat Jim Graves, who has been running even with the right-wing congresswoman, will probably face an uphill challenge against a mainstream Republican candidate. The Democrats' only hope is that movement conservatives will dominate their party convention and nominate someone like State Senator Mary Kiffmeyer. She has criticized the separation of church and state and once defended a conservative advocacy group's statement that "racially pure" countries tend to have better health-care outcomes.

Bachmann's departure is a blow to national Democrats for another reason: The failed 2012 Republican presidential hopeful had become a favorite target for her often inflammatory and mistake-filled assertions.

Even so, of more immediate concern to Democratic political strategists in Washington is the June 25 special election in Massachusetts to fill the Senate seat of Secretary of State John Kerry. The Democratic candidate, U.S. Representative Ed Markey, they say, is running a campaign that is too cautious and is too reliant on a large contingent of longtime advisers. And the message is too often mixed.

Nevertheless, Democrats expect to retain that seat because the Republican candidate, Gabriel Gomez, is a political neophyte and often seems uninformed on even basic issues.

(Albert R. Hunt is a Bloomberg View columnist. Follow him on Twitter.)