CHICAGO -- A longtime Republican district fell to the Democrats Saturday when wealthy scientist and businessman Bill Foster snatched former House Speaker Dennis Hastert's congressional seat in a closely watched special election.

Click Here For Results Video: Foster Wins Video: War Of Words Over Advertising Video: Watch 'City Desk' With Foster, Oberweis Story: Did Oberweis Make Fun Of Foster?

Foster won 53 percent of the vote compared to 47 percent for Republican Jim Oberweis with 100 percent of precincts reporting.

"Tonight our voices are echoing across the country, and Washington will hear us loud and clear: It's time for a change," Foster told cheering supporters.

Bill Foster spent the day Sunday thanking his supporters.

Foster said his first task in Washington will be to determine on which committees he sits, and then he will work on extending health insurance programs for children.

With less than 20 percent of registered voters turning out for Saturday's special election, some Oberweis supporters said the dairy owner has a much better chance of winning in November, when the two face off again for the full two-year term.

Because of absentee and overseas votes from the military, the results of the special election might take up to a month to certify. However, the state Democratic Party is working to get Foster sworn in before then, so residents in the 14th District have a voice in Congress as soon as possible.

Democratic Congressional Campaign Committee Chairman Chris Van Hollen said Foster's win is a rebuke of the Bush administration and of the GOP's apparent presidential nominee, John McCain, who campaigned for Oberweis.

"Bill Foster's victory ... sends a political shock wave across America this election year," Van Hollen said in a written statement.

Foster's special election win means he will fill the remainder of Hastert's term until it ends next January. The 66-year-old Hastert, who lost his powerful post as speaker when Democrats took control of Congress, resigned late last year.

Foster, 52, worked for 22 years at the Fermi National Accelerator Laboratory. He got his start in business when as a young man he and his brother started a company that manufactures theater lighting equipment.

Oberweis, whose name is synonymous with his family's dairy business and his financial management company, gets another shot at the seat when he squares off again with Foster in November for a new, full term. Foster won a close Democratic primary by less than 400 votes for that race, although one challenger has initiated a recount.

"I'm really disappointed that we came up second but that's where we're at," said Oberweis, who had Hastert's backing in the race.

This is the latest election disappointment for Oberweis who has lost primary races twice before for the U.S. Senate and once for Illinois governor.

With Foster headed to Washington, the district will have a rookie congressmen after years of enjoying Hastert's clout. During his 21 years in Washington, Hastert funneled millions of dollars to the district that stretches from Chicago's far western suburbs to almost the Mississippi River. Foster lives in Geneva.

Hastert's is one of three open seats in Illinois this year because of GOP retirements. Reps. Jerry Weller, who represents a district from the suburban sprawl south of Chicago to the farmland of central Illinois, and Ray LaHood of Peoria are also stepping down. Democrats' chances to pick up one of those seats improved when the Republican nominee to replace Weller dropped out of the race.

Besides poking at each other with negative TV ads, Foster and Oberweis have clashed on issues from immigration and health care to the Iraq war.

During a recent TV appearance on NBC5's "City Desk," Foster said he would be a "good vote in Congress to change President Bush's policy" on Iraq. Oberweis contended the troop surge there was working, saying: "Things are getting better in Iraq."

Oberweis also has blasted Foster for being a proponent of big government because Foster says he wants to move toward universal health care. Foster claims Oberweis' approach -- he favors tax incentives to help people buy their own insurance -- only works for people who are "healthy and wealthy."