DOVER — Democrats seeking the state’s open seat in the U.S. House of Representatives continue to pull in big money. For the second consecutive quarter, the three front runners in the primary contest raised at least $135,000 apiece.

Sean Barney led the way with $211,000 in the second quarter of 2016, although state Sen. Bryan Townsend, with $535,000, has raised the most money thus far.

Sen. Townsend received $176,000 from April 1 to June 30, and former state Labor Secretary Lisa Blunt Rochester raised $138,000 in donations in that time period.

Republican Hans Reigle pulled in $37,000, giving him $123,000 total.

Sean Barney

Mr. Barney, a former staff employee of Sen. Tom Carper, D-Del., and Gov. Jack Markell, has raised $442,000 since entering the race in December. He reported having $279,000 on hand.

“I’m proud that for the second quarter in a row my campaign has out-raised our competition,” he said in a statement. “Our financial strength demonstrates that people are ready for leaders who will put country before self, who have a proven track record of results and who will reach across the aisle to get things done for Delaware. With momentum now firmly on my side heading into the home stretch, I am confident that I will win this race.”

Sen. Townsend, who represents the Newark area, had about $248,000 available.

“Just as important as how much we raised is how we raised it,” he said in a statement. “Seventy percent of our donors are from Delaware and the majority of their donations are for $100 or less. We are proud to be supported directly by Delawareans first and foremost, rather than be a campaign that relies heavily on out-of-state donors or Super PACs.”

Ms. Blunt Rochester, who announced a run in October, has pulled in $395,000 in total, with $320,000 on hand. She has loaned her campaign about $179,000.

“We are so proud of the hundreds of grassroots donors who are supporting Lisa’s historic campaign for Congress,”

Lisa Blunt Rochester

campaign manager Max Glass said in an email. “Over these final 60 days, we continue to build a strong campaign and — with the highest cash on hand in the race for the 3rd quarter in a row — are in an excellent position to communicate Lisa’s positive message to Democratic primary voters.”

Mr. Reigle, the former mayor of Wyoming, had $57,000 on hand as of the end of June. His donors include state treasurer Ken Simpler and a political action committee run by former Gov. and U.S. Mike Castle.

OpenSecrets.org, a watchdog group that focuses on campaign spending, reported that as of the end of March, about 74 percent of Mr. Barney’s money had come from out of state, 39 percent of donations to Sen. Townsend were from outside Delaware and 36 percent of contributions to Ms. Blunt Rochester came from another state. Thirty percent of Mr. Reigle’s donations originated out of state.

Current officeholder John Carney, a Democrat, is running for governor, creating a free-for-all among candidates seeking to replace him.

Finance information for Democratic candidates Mike Miller, Scott Walker and Elias Weir was not available.

The primary is Sept. 13.