Maryland leans Democratic, but not as much as the party’s 7-to-1 dominance in the state’s delegation in the House of Representatives suggests. After all, a Republican governor, Larry Hogan, now entering his final year in office, has been elected twice by comfortable margins; GOP voters outnumber Democrats in most of the state’s rural and exurban counties.

For Democrats who control Maryland’s legislature, that inconvenient fact, coupled with brazen Republican gerrymandering in states the GOP controls, seems to have only stiffened their resolve to lock in their advantage by gerrymandering the electoral map, already among the most preposterously partisan in the country. Heedless of public opinion and the recommendations of a citizens commission, Democratic lawmakers in Annapolis appear determined to draw congressional districts even more tilted in their favor than the ones they established 10 years ago.

Granted, it’s rich to hear the righteous indignation of Maryland Republicans, who have been silent as their counterparts in other states are busy in this decennial redistricting year skewing maps in their own partisan favor. Politicians choosing voters of their liking, rather than the other way around, is unquestionably bipartisan.

Large majorities of Americans are fed up with being used as pawns on electoral maps, to be shifted, sliced, severed and rearranged in service of sustaining a majority party’s grip on power. Gerrymandering is also accelerating the nation’s descent into tribal dissolution. Confident that the outcome of general elections in congressional races is a foregone conclusion, the most extreme voices compete with one another in primaries in the sure knowledge that they will never have to pivot to appeal to centrist and swing voters.

Ten states have redistricting commissions, replacing partisan control with bipartisan or nonpartisan bodies designed to produce more evenhanded maps. In Maryland, Mr. Hogan unsuccessfully tried to advance legislation that would have created a commission to draw congressional maps. Blocked by State House Democrats, he finally this year issued an executive order establishing a bipartisan citizens commission on redistricting. The commission, an advisory body with no power, produced a fair-minded congressional map, which Democrats have rejected in favor of one that enhances the gerrymander they pushed through a decade ago.

The map drawn by Mr. Hogan’s citizens commission was awarded an A for partisan fairness by the Princeton Gerrymandering Project. The one favored by Democrats got an F, based partly on tortuous districts that ignore county lines, the better to tilt the playing field in next year’s midterm elections and thereafter. Democrats’ districts make a mockery of compactness and contiguity, two traditional standards of nonpartisan map-drawing.

There is no secret about Democrats’ agenda. They aim to unseat the state’s lone Republican in Congress, Rep. Andy Harris, who represents the 1st District, on the Eastern Shore. The map would reconfigure the district, hopping across the Chesapeake Bay to include some Democratic precincts of Anne Arundel County.

That naked bit of partisanship is no different from what GOP lawmakers have done in states they dominate. And it is no better.