Illinois Senate Democrats released a map of state legislative districts Thursday morning, setting off a scramble among Republicans who played no role in the process.

The map will dictate the boundaries of General Assembly districts for the next 10 years. It still must be reconciled with a House map, but both versions are said to be similar. The House and Senate scheduled a joint redistricting meeting for Tuesday. A hearing on the Senate proposal is set for noon Saturday at the Michael Bilandic building in downtown Chicago.

The map protects federally-mandated Latino and black districts, mostly in Chicago and its near suburbs. It was designed to give Democratic incumbents an edge during the next 10 years of General Assembly elections by including pockets of heavily-Democratic voters in each district.

The Democrats controlled the process because they hold majorities in the Illinois House and Senate. The final say belongs to Gov. Pat Quinn, also a Democrat.

A map of congressional districts has not yet been released.

On the state map, the Chicago area resembles bicycle spokes with districts snaking from the city’s Democratic boundaries into the suburbs.  Due to population losses in Chicago, most districts shifted south and west, or north and northwest. Some districts were nearly eliminated.

State Rep. Kevin McCarthy (D-Orland Park) loses much of his southwest suburban base under the new map. So does Democrat Lisa Dugan (D-Bradley) who is pushed into Central Illinois.

Other districts, however, strengthen or maintain re-election prospects for incumbents. Democratic House Speaker Michael Madigan’s district stays mostly intact under the new map with Midway Airport as an anchor. His Southwest Side neighbor, state Rep. Dan Burke (D-Chicago), loses suburban precincts in Berwyn but picks up more swaths of the city.

“It’s significantly different, but the demographics are not changing,“Burke said.

Burke has represented one of the state’s highest Latino-populated districts for a decade. Under the new map, his Latino base drops from about 87 percent to about 76 percent.

Two House districts make up one Senate district. The target population for the state’s 59 Senate districts was 217,468.

Republicans are expected to face a tougher road in the 2012 elections based on where their incumbents will be running. Their own Senate leader, Christine Radogno of Lemont, could face-off with a colleague. Districts are drawn to accommodate incumbents’ homes, and hers is included in the same district as state Sen. Ron Sandack of the Lombard area.

Radogano was tossed into a colleague’s Senate district 10 years ago as well. Then, she faced a GOP primary election with state Sen. William Mahar of Orland Park and beat him.

She could not be immediately reached for comment.

Kristen McQueary reports on Illinois state government for WBEZ and the Chicago News Cooperative.