COLUMBIA (AP) — A bill heading to the Senate floor is designed to curtail candidates’ ability to hide who’s backing their campaigns.

The bill advanced Tuesday would reduce the pre-election black-out period for disclosing donations from 20 days to five.

Sponsoring Sen. Paul Thurmond had hoped to eliminate the black-out period candidates use to hide controversial donors until after an election. The Charleston Republican said voters should be able to find out where candidates get their money. He said the amended version represents an improvement he’s willing to accept.

The House is expected to debate its broader ethics reform package this week. House Republicans drew fire after the bill was posted online last week over a section that decriminalizes some violations. They said that was unintentional and will be fixed on the floor.