IN ANNAPOLIS LAST year, the Democrats who exercise monopoly control over state politics rammed through a congressional redistricting map whose over-the-top cartographic squiggles, shards, tendrils, ringlets, claws and loop-the-loops make a mockery of democracy. Now, some principled grass-roots Democrats, disgusted at the map’s heavy-handed partisanship, are breaking party ranks and urging the state’s voters to reject it when they have the chance in a ballot referendum in November.

In a bracing challenge to their party’s elected leadership, a panel composed of Montgomery County Democrats has urged that the sample ballot distributed to the party faithful this fall include a “no” vote on the redistricting map. The sample ballot is sent to about 250,000 registered Democrats in Montgomery.

The panel’s vote is merely advisory; it may be disregarded by county Democratic officials this month. Even if it stands, defying Gov. Martin O’Malley and the rest of the state Democratic leadership, other Democrats may not take heed.

They should. The map is so ludicrously drawn — and so crassly gerrymandered — that one critic, Montgomery County Councilman Phil Andrews, said the map of the Third Congressional District “looks like blood spatter from a crime scene rather than a congressional district.” (It manages to connect parts of Silver Spring, a few miles from the D.C. border, with Towson and Owings Mill, in suburban Baltimore, and Annapolis — three distinct parts of the state linked on the map by wisps of terrain.)

The map’s comical gyrations were devised mainly for the purpose of obtaining a seventh Democratic seat from the state’s eight congressional districts. The idea was to weaken the Republican hold on the Sixth Congressional District, held for 20 years by Rep. Roscoe Bartlett; as Democrats intended, he now faces a stiff electoral challenge in the redrawn district.

The best outcome would be for Maryland voters to reject the map, sending it back for a major overhaul in Annapolis. That wouldn’t alter the results of November’s elections, nor would it wrest redistricting from Democratic control. However, it would deliver a badly needed reprimand to a party whose arrogant manipulation of voting lines is an embarrassment to the state.

The usual defense heard in Annapolis — that Republicans do the same elsewhere (see: Texas, 2002) — is just a rationale for lowest-common-denominator politics. The effect of baldfaced partisan redistricting is to cement a stultifying status quo of non-competitive elections whose winners are all but guaranteed a lifetime lock on congressional seats. Lacking any incentive to compromise across the aisle or to court political centrists, these congressmen-for-life have delivered what most Americans have come to loathe: a dysfunctional legislative branch and paralysis in Washington.

Party leaders such as Mr. O’Malley could have embraced a bipartisan or nonpartisan redistricting system, which in various forms has been adopted in about a dozen states. Those systems have the potential to produce more moderate candidates and more competitive districts — in other words, a real choice for voters. Instead, Mr. O’Malley has scoffed at the idea, suggesting he will stick by the Maryland map with minor tweaks even if voters reject it. That’s the sort of arrogance that can lead voters to reassess their party allegiance.