A Maricopa County Superior Court judge will hear arguments Friday on dropping the five individual redistricting commissioners from a lawsuit challenging their congressional districts map.

The lawsuit, brought by Republicans who said the Arizona Independent Redistricting Commission favored Democrats in adopting the map boundaries last year, alleges the commission violated procedural requirements.

The suit seeks to bar repeat use of the congressional districts used in last fall's elections and to require the commission to draw a new map.

Commission lawyers are expected to argue that the individual commissioners should be dropped as defendants because they individually cannot approve new maps, something only the commission as a group can do.

The plaintiffs contend the commission's motion is an attempt to shield individual commissioners from pretrial fact-finding.

The congressional map of nine districts has four with majority Republican registered voters, two with majority Democratic registered voters and three considered competitive because the split between Republicans and Democrats is close.

Voters elected Democrats in five districts and Republicans in four in the 2012 election.

In a separate case, Republicans also have challenged the commission's legislative map, saying it was drawn to give Democrats proportionally more seats than their registration numbers should allow. A Superior Court decision in that case is expected soon, with appeals anticipated.