CHICAGO (CBS) – A local political expert said Wednesday that Illinois House Speaker Mike Madigan’s remap of the state’s voting districts proved to be very successful for the Democrats.

WBBM Newsradio Political Editor Craig Dellimore reports four Congressional seats changed hands from Republicans to Democrats on Tuesday, and Democrats also tightened their grip on control of the Illinois General Assembly.

For example, traditionally Republican DuPage County will have its first Democratic state senator when the new General Assembly is sworn in in January. A new Democratic state representative also will come from DuPage.

LISTEN: WBBM Political Editor Craig Dellimore Reports

Not only did Democrats retain control of both the Illinois House and Illinois Senate, they actually tightened their grip on both chambers.

Democrats picked up seven seats in the Illinois House, to gain a veto-proof majority of 71-47. In the Illinois Senate, where Democrats already had a veto-proof majority, Democrats will outnumber Republicans 40-19 starting next year – more than a 2:1 advantage. Those gains not only weaken Republicans, they also weaken Gov. Pat Quinn, who can no longer veto legislation passed without fear lawmakers from his own party will override him.

Northern Illinois University political science professor Matt Streb said the big win for Democrats was partly because redistricting by Madigan and other party bosses shifted Republican voting blocs around to improve Democrats’ chances of winning more seats in the legislature.

“Maybe you take some of the Republicans, and you put them into [Congressman] Mike Quigley’s 5th District. That was actually where [Congresswoman] Judy Biggert’s old home was in Hinsdale. Well, that’s now part of Quigley’s 5th District,” Streb said. “So instead of winning with 68 percent of the vote, maybe Quigley wins with 63 percent of the vote, but he still wins very easily.”

Biggert lost to former colleague Bill Foster in the newly redrawn 11th District.

Streb said the redistricting also helped Democrat Bill Foster defeat Biggert in the newly drawn 11th District, and also helped the Democratic Party get three members of Congress representing portions of DuPage County – Foster, Quigley, and Tammy Duckworth, who defeated 8th District incumbent Congressman Joe Walsh.

Redistricting also likely played a role in rookie candidate Brad Schneider’s upset win over 10th District Congressman Bob Dold, and Cheri Bustos’ win over 17th District incumbent Bobby Schilling.

But Streb said he’s not sure the Democratic advantage in Illinois will last an entire decade until the next redistricting, especially since three of the four new Democratic members of Congress are freshmen.