A bill in the Hawaii Legislature would give voters more information about who is spending money on campaign ads.

The proposal would require super PACs and other non-candidate committees to file an additional campaign spending report earlier in the election cycle.

As it stands now, a preliminary spending report is due 10 days before the general election. But that falls after early voting begins in Hawaii, so some voters cast ballots before the reports are available to the public. Polls open for early voting in Hawaii about two weeks before Election Day.

"What we're doing is trying to make sure people have that information before they go in and vote," said Sen. Gilbert S.C. Keith-Agaran, chairman of the Senate Committee on Judiciary and Labor. "One of the big examples this year was super PACs that were involved in the GMO initiative on Maui. It wasn't until 10 days before the election that it became apparent that the spending in that particular initiative in one county was the most-ever spent in any campaign in the state."

In the 2014 election cycle, super PACs spent $10.2 million on ballot initiatives and $5.9 million on candidates, according to Common Cause Hawaii, which supported the bill. A political action committee called Citizens Against the Maui County Farming Ban, backed by biotechnology companies, spent nearly $8 million on a massive campaign to fight the Maui voter initiative, which sought to ban cultivation of genetically modified organisms.

But until those campaign spending reports are filed, it's not always clear who is behind the messages that dominate the airwaves.  "If there's a report 10 days before an election, people who vote early are not going to see that," said Barbara Polk, interim chairwoman of Common Cause Hawaii.

The bill -- SB 508, introduced by Sen. Laura Thielen -- initially suggested changing the due date for the preliminary spending report from 10 days before the election to Oct. 1. But the state Campaign Spending Commission pointed out that would result in more than a month of campaign spending that was not reported until after the election.

"You're going to have a longer period of time that's not going to be reported," said Gary Kam, general counsel for the Campaign Spending Commission.

Keith-Agaran recommended amending the bill so that it would require reports both on Oct. 1 and 10 days before the election, he said.

The Senate Committee on Judiciary and Labor passed the amended bill on Friday.