New Haven - A former state representative has won a costly Democratic primary for Congress, defeating the Connecticut House speaker whose run was dogged by a campaign finance scandal.

Former state Rep. Elizabeth Esty won the race for the 5th District primary. Speaker Chris Donovan was the Democratic Party's endorsed candidate, but a federal investigation led to charges against his former campaign finance director and campaign manager.

"Shoe leather works. Grass roots works. And we are going to need it in November," Esty said.

Donovan's aides were arrested for allegedly participating in a scheme to hide the source of $27,500 in campaign contributions. Authorities said the donations were tied to an effort to defeat legislation that would have raised taxes on "roll-your-own" smoke shop owners.

Donovan has denied any knowledge of the alleged conspiracy and hasn't been charged.

"While I won't be the Democrat nominee in November, I will continue fighting for the progressive causes I've always fought for and I'm going to be there fighting with you," Donovan told supporters.

Donovan has been endorsed by the Working Families Party, but it's unclear whether he plans to proceed as a third party candidate in the 5th District race.

Esty led in fundraising. She was endorsed by Emily's List, a group that backs Democratic women who support abortion rights.

With nearly $10 million raised and $7 million spent, the 5th District race is the fourth most expensive House race in the country and the most expensive in state history, according to the Center for Responsive Politics. Several super PACs have gotten involved in the race.

The seat, which covers a largely bipartisan district in northwestern Connecticut, is one of only two U.S. House seats in New England where an incumbent is not running for re-election.

The seat was held by U.S. Rep. Chris Murphy, who is running for Senate and won the Democratic primary.

Both Esty and another candidate in the Democratic primary, Dan Roberti, flooded voters with TV ads and mailers, some taking aim at Donovan and the scandal.

On the Republican side of the 5th District race, state Sen. Andrew Roraback, R-Goshen, won a four-way Republican primary.

"I want to thank my competitors for running a spirited race and I look forward to them getting on our team because we're going to win this race by having all Republicans work together and by appealing to the unaffiliated voters who have had enough of President Obama and what the Democrats in Washington are doing to this country," Roraback said. "Things have got to change and they have to change now."

Roraback, the endorsed Republican candidate, defeated veteran Justin Bernier and business owners Lisa Wilson-Foley and Mark Greenberg.

Roraback is considered a moderate Republican in the General Assembly - a designation some of his challengers used as a criticism.

Roraback said last week that a liberal super PAC was targeting him in the GOP primary to keep the seat safe for Donovan, whom he called a "potential felon."