Democrats tried but failed to undo HB 75 this year with a bill of their own. It was tabled then died late last month. Now the commissioners are urging the court to expedite their case and issue an order before the candidate filing period in June.

The new boundary lines slice through Strafford County’s two most populous cities, Dover and Rochester, and leave two of the incumbents together in the same district, so they won’t both be able to advance from the Democratic primary to the general election this fall.

George M. Maglaras, who is serving his 20th two-year term on the commission, said the changes were a ploy to ensure that not all the incumbents could win reelection.

“The gerrymandering was done on purpose. … It was designed to destroy the commission,” he said.

Maglaras joined with fellow incumbent commissioners Deanna S. Rollo and Robert J. Watson as plaintiffs in the suit filed Monday against New Hampshire Secretary of State David M. Scanlan and Attorney General John M. Formella.

A spokesperson for Scanlan referred questions Tuesday to Formella’s office, and a spokesperson for Formella said the attorney general’s office was reviewing the lawsuit but would not comment on pending litigation.

While Democrats have slammed HB 75 as a partisan power grab, the law’s proponents contend it corrected a problem and made election rules in Strafford County more closely resemble New Hampshire’s other nine counties, which already had commissioner districts.

Senator James P. Gray, a Republican from Rochester, rejected the notion that he or anyone else who supported HB 75 had done so with nefarious intent. This is about ensuring the voices of voters are heard, he said.

“The population of Strafford County is more concentrated in the southern part of the county, and right now that population does not share all of the political views of the people in the northern part of the county,” he said.

Some constituents had complained about their inability to get candidates elected who align with their views, so adding in the districts helps to further localize electoral representation, Gray said.

The three GOP candidates who ran in 2022 did not win a single seat, even though they carried about 41 percent of the countywide vote.

Republican Representative Len Turcotte of Barrington told his colleagues last June that HB 75 would put an end to a decades-long trend of “de facto gerrymandered elections” in Strafford County.

The debate over the merits of HB 75 as a tool to enhance representation might be irrelevant, however, to the outcome of this lawsuit. The central allegation in this case is procedural: The commissioners allege state lawmakers lacked authority to draw any new county commissioner districts in 2023 because such maps were already finalized in 2022 through the once-a-decade redistricting process.

“So that voters and elected officials may have stability and continuity in the electoral process, once a valid redistricting law has been enacted, the legislature cannot redistrict again until after the next census,” the plaintiffs’ attorney, William E. Christie, said in a statement.

Maglaras said HB 75 sets a terrible precedent that could unleash confusion and turmoil whenever legislative power in Concord shifts from one party to the other.

“It’s going to create chaos,” he said.

Gray said the concerns about HB 75 are misplaced. He contends lawmakers had every right to add districts where there had previously been none, and now that the districts are in place, they are locked in.

“I consulted several attorneys that said that ‘districting’ and ‘redistricting’ are separate things, and that it was perfectly legal to district an entity that had not been districted before,” he said.

“But now that it is districted, there would be a prohibition against redistricting it until the next census,” he added.

A spokesperson for House Speaker Sherman A. Packard said the legislature can propose to modify or repeal HB 75 like any other law, and the question of its constitutionality is now in the court’s hands.

County commissioners across New Hampshire are generally tasked with oversight of county government departments and budgetary matters. Some serve two-year terms. Others serve four-year terms that may be staggered.

While commissioners must live in the districts they represent, not all them are elected solely by the voters in their district — in Carroll and Sullivan counties, each district’s commissioner is picked through a countywide vote.

Steven Porter can be reached at steven.porter@globe.com. Follow him @reporterporter.