Some House members may have angered business groups by voting for the Disclose Act on Thursday.
Three members who received campaign donations this cycle from the Chamber of Commerce's PAC voted for the bill, which passed 219 to 206.
Rep. Mike Castle (R-Del), a co-sponsor of the legislation, along with Reps. Adam Smith (D-Wash.) and Henry Cuellar (D-Texas) voted in favor. The members each have received $1,000 from the Chamber this cycle. Castle is running for Senate in Delaware and observers say his vote will likely help him appeal to some Democrats.
The Chamber and its allies opposed the legislation that will bolster disclosure requirements for corporate and union spending because they believe it puts unconstitutional limits on free speech.
Rep. Brad Ellsworth (D-IN), who the Chamber has spent independent expenditure money supporting with radio ads, also voted for the bill. Strategists told The Ballot Box it may help him hone a pitch as a Washington reformer during his Senate run.
Meanwhile, three other House Democrats who the Chamber has backed financially voted against the bill's passage -- Reps. Walt Minnick (D-Idaho), John Barrow (D-Ga) and Melissa Bean (D-Ill.).
Rep. Dan Boren (D-Okla.), who got the Chamber's endorsement on Wednesday, also voted against the bill.
The measure won just two Republican votes in the House, Castle and Rep. Joseph Cao (La.). The freshman Republican from Louisiana holds one of the most Democratic districts in the country, which likely influenced his decision.
Rep. John Boozman, the GOP Senate nominee in Arkansas, voted against the bill, prompting a rebuke from Democrats. "Congressman Boozman might make the special interests happy with his voting record, but he sure isn’t building any goodwill with Arkansas families," Deirdre Murphy, a spokeswoman for the Democratic Senatorial Campaign Committee, said in a statement.
The legislation now moves to the Senate, where business groups will have another chance to derail its passage. President Obama urged the upper chamber to "act swiftly" on the bill.
--Shane D'Aprile contributed to this post.
--This post was updated and corrected on June 25.