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

Democrat Bill Foster won 52 percent of the vote compared to 48 percent for Republican Jim Oberweis. With 565 of 568 precincts reporting, Foster had 51,140 votes to Oberweis' 46,270.

"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 Saturday evening.

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 helped raise money for Oberweis.

"This is going to send a political shock wave across the country in this election year," Van Hollen said.

Foster's special election win means he will fill the remainder of Hastert's term, which ends in January.

The two will square off again 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 re-count.

Hastert, 66, lost his powerful post as speaker when Democrats took control of Congress. He resigned late last year.

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

The race spawned a contentious campaign that saw both men turn to high-profile supporters to help sway voters. Democratic presidential candidate Barack Obama made a TV ad praising Foster; Oberweis had Hastert's backing.

"I'm really disappointed that we came up second but that's where we're at," said Oberweis, whose name is synonymous with his family's dairy business and his financial management company.

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.

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.

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.

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.

In southeast Louisiana, voters cast ballots in two congressional districts Saturday to find replacements for longtime Republican congressman Richard Baker and newly elected Republican governor Bobby Jindal.

In the 1st Congressional District, state Sen. Steve Scalise had about 40 percent of the vote in the pivotal GOP race with 277 of 505 precincts reporting. On the Democratic side, Gilda Reed, an adjunct professor at the University of New Orleans, had 70 percent.

The winner of the GOP contest will be the strong favorite to win Jindal's seat because of the district's strong conservative leaning.

In the 6th Congressional District, state Rep. Don Cazayoux had about 49 percent of the vote in the Democratic primary with 222 of 512 precincts counted. On the GOP side, former state House member Woody Jenkins led with about 51 percent.

This was the first time since the 1970s that Louisiana saw closed party primaries in federal elections.