House Democrats have locked down at least one Republican vote for a new campaign finance bill that is expected to debut this week.

In a statement released Monday, Democratic Congressional Campaign Committee Chairman Chris Van Hollen (Md.) said a deal has been reached with Rep. Mike Castle (R-Del.), a campaign finance reform veteran whose support represents a bipartisan breakthrough for the long-awaited bill. Although few details were released Monday night, the legislation is expected to counter the Supreme Court’s recent decision in Citizens United v. Federal Election Commission, which lifted most federal restrictions on television ad buys by corporations, trade associations and nonprofit organizations.

The lawmakers on Monday also declined to indicate when a final proposal would emerge, other than to say it would be introduced “shortly.”

“The bipartisan legislative response to this ruling will promote openness in government and compel disclosure of the money that is being used to finance elections,” the Members said in a joint statement with few details. “The Court’s ruling in this case demonstrates a blatant disregard for its own precedents and ignores the clear intent of Congress to reduce the influence of powerful special interests.”

Castle is running to replace retiring Sen. Ted Kaufman (D-Del.), the onetime Senate aide to Vice President Joseph Biden who took Biden’s seat after the 2008 presidential election.