The Maryland Democratic Party joined with five other plaintiffs Tuesday in bringing a legal challenge against the State Board of Elections for allowing a referendum to move forward on Maryland’s new congressional map.

In a complaint filed in Anne Arundel County Circuit Court, the Democrats alleged that opponents of the map submitted “substantially fewer valid signatures” than the state board had verified.

In a letter last week, State Elections Administrator Linda H. Lamone said elections officials had counted 59,201 signatures, exceeding the 55,736 needed for the issue to be put before voters in November.

The Democrats contend that more than 5,000 signatures should not have been counted because of several technical reasons, including forms on which address and other information was generated by computers rather than the signers.

“The Maryland Democratic Party is committed to ensuring confidence in and protecting the integrity of the petition process, and has taken appropriate steps to do so today,” said its executive director, David Sloan.

Opponents of the congressional map, led by Del. Neil C. Parrott (R-Washington), argue that it is severely gerrymandered.

“Frankly, I’m surprised Maryland Democrat leaders are suing to stop the people of Maryland from voting on the redistricting map this coming November,” Parrott said Tuesday, “The current map suppresses minority voting interests and divides communities. With this lawsuit, they are actively working to suppress voters throughout Maryland.”