A T-shirt showing Maryland’s 3rd Congressional District. (Kate Patterson/For The Washington Post)

FOR THE first time in years, Maryland has a real opportunity to shed its grotesquely gerrymandered electoral districts, for both Congress and the state legislature, and replace them with maps drawn by an independent commission whose purpose would be to elevate the interests of voters over those of insider politicians. Incumbent Democrats, who rule the roost in the status quo, are threatening to block just such a change, in the form of a constitutional amendment proposed Tuesday by Gov. Larry Hogan, a Republican. They would be foolish to do so.

It’s not hard to make the case for redistricting reform in Maryland, where Democrats enjoy a 2-to-1 advantage in voter registration but a 7-to-1 advantage in the state’s eight-member congressional delegation. Unsurprisingly, Democratic incumbents are happy with this arrangement; Republicans, to say nothing of anyone who values genuine democratic competition, fair elections and a robust two-party system, correctly see a rigged system.

Mr. Hogan has said Maryland’s electoral maps, variously likened to a “blood spatter from a crime scene,” a “broken-winged pterodactyl” and a praying mantis, are an embarrassment to the state. His answer was to establish a commission to propose an overhaul to the current system, which it did in the fall.

In keeping with those suggested reforms, Mr. Hogan has now offered a constitutional amendment that would shift the process to an independent nine-member panel that would formulate district maps without regard to voter registration data or voting history. That would represent a radical departure from the status quo, under which the governor generally controls congressional redistricting after each decennial census, and the General Assembly manages redistricting for its own legislative districts.

Even before the commission formulated its recommendations, Democrats, who control the General Assembly, sneered at the plan — or any prospective plan — as a Republican plot that would be immediately euthanized. The Democrats’ ostensible objection is that it amounts to unilateral disarmament on their part, unless undertaken in concert with other (read: GOP-controlled) states.

That’s a cop-out — about 10 states have already moved to some version of non- or less-partisan redistricting. But let’s take the Democrats at their word. If their real fear is going forward alone, and risking the loss of a few seats in Congress and the General Assembly, why not invite Virginia along for the ride?

After all, Virginia is Maryland’s political mirror image, a state where a Democratic governor is stymied by a Republican-controlled legislature. Republican gerrymandering in Virginia has been almost as shameless as Democratic gerrymandering in Maryland. So why doesn’t Maryland’s Senate president, Thomas V. Mike Miller Jr. (D-Calvert), place a call to Virginia’s majority leader, Thomas K. Norment Jr. (R-James City)? For that matter, why doesn’t Mr. Hogan suggest a two-state solution to his opposite number in Virginia, Democratic Gov. Terry McAuliffe?

In any event, Democrats in Annapolis should think carefully before killing off reform. If there is no change and Mr. Hogan is reelected in 2018, he will be the guiding hand in Maryland’s congressional redistricting come 2021.