COLUMBIA - A compromise Wednesday on South Carolina's first ethics reform package in two decades stripped a proposal critics had called essential but moved forward with other reforms to pave the way for the bill's passage.

A joint House-Senate conference committee killed an independent investigative panel that would have had the power to look into ethics complaints against members of all three branches of government. Disciplinary decisions would have been left up to the current bodies that decide those matters.

A committee report is expected to be formally signed off on Thursday and voted on by both chambers. Lawmakers said they expect it to pass.

Critics have complained that because respective House and Senate ethics panels are responsible for both investigating and disciplining members of their own body, it's akin to the fox guarding the henhouse. They called on lawmakers to pass a bill that included an independent investigative body so complaints couldn't be swept under the rug.

A spokesman for Gov. Nikki Haley called the bill a first step. "Let's be clear, this is an income disclosure bill, not true ethics reform," said Doug Mayer, Haley's spokesman, in a statement. "While income disclosure is an important step forward, as always, the governor will review what the conference committee approved."

Senators on the six-member conference committee said that the proposal didn't have enough votes to pass in that chamber. Senators had already rejected a similar proposal earlier this year.

"Perception is extremely important when it comes to ethics," said Sen. Wes Hayes, R-York. "We tried in the Senate to get consensus on this but we could not get it this year. I don't think it's something we need to give up on."

The bill did achieve what Hayes calls the "big three" issues: ensuring that lawmakers disclose their sources, although not amounts, of their private income; requiring groups and Super PACs that spend money on campaigns in South Carolina to disclose their donors; and banning so-called Leadership PACs, lawmaker fundraising groups that raise funds and then spend dollars without the oversight and scrutiny of campaign funds.

The measure also sets up a committee to study what parts of the Ethics Act should contain criminal penalties. As it stands, all violations, inadvertent or not, can be prosecuted as criminal misdemeanors.

The reform initiative comes as ethics investigations have plagued both chambers. House Speaker Bobby Harrell, R-Charleston, is being investigated by a state grand jury for allegedly using campaign funds for personal use, including funds that paid for office-related trips on his personal airplane.

Former Sen. Robert Ford, R-Charleston, resigned in 2013 after revelations that he bought adult toys and other items using funds allocated for his campaign or office use. Last month, the Senate Ethics Committee hammered former state Sen. Robert Ford with nearly $45,000 in fines for ethics violations.

Critics have blasted the reform effort, saying that lawmakers have stumbled to address the ethics issue from the beginning.

"They're really just playing around the edges around all of this stuff," said Ashley Landess, president of the small government advocacy group South Carolina Policy Council, who brought the original ethics complaint against Harrell. "We want thoughtful legislation that actually addresses the problem."

Landess and others have called on lawmakers to limit or do away with the ability to use campaign funds for office uses, the subject of much controversy. The ethics measure the House and Senate will consider further defines office uses, Landess said, which could open up further abuse of those funds.

"They've defined the gray area on their terms and that's not what anybody wanted," Landess said.

She urged lawmakers to study the bill before passing it Thursday, the last day of the official legislative session.

Reach Jeremy Borden at 708-5837.