Gov. Martin O’Malley’s (D) controversial redistricting plan passed the House of Delegates on Wednesday, but with technical changes that will require the state Senate to reconvene on Thursday to amend its version before the measure can be signed into law.

Republicans and five House Democrats voted against the measure, but it still passed with a needed supermajority to ensure it can be enacted in time to let Maryland hold its primary, scheduled for April 3.

Senate leaders said they were confident the plan would pass a final vote on Thursday.

O’Malley’s congressional redistricting plan has been criticized by Rep. Donna F Edwards (D) and some other African American and Hispanic lawmakers in Montgomery County for the way it would divvy up the county’s majority minority population across three mostly white districts. Edwards has said the net effect will be that minorities will not be able to elect anyone other than a white lawmaker for years to come.

Republicans are concerned that the plan adds more Democrats to Rep. Roscoe Bartlett’s (R) district, threatening Bartlett’s re-election prospects and potentially giving Democrats seven of Maryland’s eight congressional seats.

Republican House leader Del. Anthony J. O’Donnell (R-Calvert) said it was no surprise that the plan rocketed through the chamber in little over 24 hours. “The books were cooked on this a long time ago,” he said, referring to the way O’Malley and the state’s Democratic-controlled legislature holds near total control over the state’s redistricting process.

All five Democrats who voted against the measure were from the Washington area. Among them were Prince George’s County delegates Aisha N. Braveboy and Tiffany T. Alston, two allies of Edwards who had attempted to lead opposition to the measure on the Legislative Black Caucus.

Montgomery delegates Alfred C. Carr, Ana Sol Gutierrez, and Luiz R. Simmons also voted against the plan.

Gutierrez also unsuccessfully argued for an amendment that would have reconfigured representation in Montgomery to hold together Hispanic and other minority communities.

Democrats also rebuffed several other proposed amendments by Republicans, including one that would have required Maryland Attorney General Douglas F. Gansler (D) to produce a legal basis for why the governor’s plan doesn’t violate the 1965 Voting Rights Act.

The Senate is scheduled to take up the measure at 10 a.m. on Thursday