COLUMBIA — South Carolina senators unanimously approved what they called the largest overhaul of state government in decades.

Thursday’s 40-0 vote returns to the House a much-amended bill abolishing the Budget and Control Board and putting many of its duties under the governor’s jurisdiction. The House approved a very different version last year. The bill will likely end up in a committee of House and Senate members to iron out differences.

Supporters say it streamlines and modernizes state government. Much of the debate involved concerns about consolidating too much power under one person — the governor. But senators say their version — following months of debate — provides greater accountability and gives more responsibility to both the executive and legislative branches.

The measure is a centerpiece of Gov. Nikki Haley’s agenda and prompted a state Supreme Court showdown with legislators last summer over calling them back into session. The bill would give her a major victory in her second year in office, should it make it to her desk.

While the House has passed similar restructuring bills several times, they died in the Senate.

Haley called the vote “unbelievably historic in the fact no one can say that South Carolina is not moving in the right direction.” The current structure is “bureaucratic at best and archaic in the eyes of every other state,” she told The Associated Press.

Sen. John Courson, R-Columbia, said it brings the state’s government structure “kicking and screaming into the 21st century.”

The measure eliminates the 1,000-employee Budget and Control Board, as of January 2013, and divvies up its various responsibilities. Workers will be dispersed as well; senators don’t expect job losses.

But it means an end to the powerful, five-member board that oversees the agency and is the final say for a broad array of state government. That includes agency deficits, employee health insurance, construction contracts, and budget reductions during downturns. It consists of the governor, comptroller general, treasurer, and chairmen of the House and Senate budget-writing committees.

“We’ve just come out of an archaic form of the big, green, ugly monster that was the Budget and Control Board,” Haley said.

Former Gov. Mark Sanford, who was often on the losing side of 3-2 votes, tried to abolish the board throughout his two terms. But contentions between Sanford and his fellow Republican legislative leaders made it increasingly impossible to create a new agency seen as giving him more control.

Sen. Tom Davis, Sanford’s former chief of staff, has long argued the hybrid commission runs counter to how government should work, by putting too much power in one body that carries out legislative and executive functions.

Haley took the measure that was largely seen as inside-the-Statehouse politics about a board few understood out on the campaign trail. She told voters about multi-million dollar computer systems that were bought but never turned on, and the inability for employees to make simple purchases.

The approved measure would put many bureaucratic functions into a new Cabinet-level Department of Administration, including property and fleet management, computer technology, human resources, and janitorial services. It is akin to agencies that exist in 48 other states.

“The core administrative functions are now the responsibility of the governor,” said Sen. Vincent Sheheen, D-Camden, who has advocated for the idea for years.

He said the bill removes politicians’ excuse to blame problems on the state’s governance structure, while giving good leaders the tools they need to effectively run government.

“The structure of government at the end of the day is only as good as the people who run it,” said Sheheen, who lost to Haley in the 2010 election.

Purchasing would be divided between the Department of Administration and a new procurement oversight board. Many senators balked at giving the governor’s office full purchasing power. But the measure calls for a joint analysis of spending across state agencies.

The idea is the state can both save money and improve services by consolidating a hodgepodge of contracts for things as basic as office and cleaning supplies, and computer hardware and software.

The measure also:

—Ends the practice of state agencies asking the Budget and Control Board for permission to run a deficit. Agencies would have to seek permission from the Legislature, which lawmakers say means agency leaders will be more practical about their budget requests and cautious about running over.

—Splits the state budget office between the Legislature and governor’s office. It provides the governor an actual budget office for creating executive proposals.

—Requires the Legislature to have more oversight of state agencies, by requiring hearings and periodic reviews.

—Requires the Legislature to return to session if revenue projections fall more than 2 percent below earlier predictions, to encourage more targeted, rather than across-the-board cuts by the Budget and Control Board — the only cuts state law allowed that group to make.

Sen. Phil Leventis, D-Sumter, said he voted “present” because there have been so many amendments to the bill, he’s not sure what’s in it. In booklet form, as of Wednesday, the measure was more than 100 pages. While the Budget and Control Board may have its problems, so will the Department of Administration, he said.

“It represents inside-baseball, not the concerns of the people of the state,” Leventis said. “The governor is the least accountable person in the state, no matter who it is.”

The measure has consumed the Senate since the legislative session started six weeks ago.

Floor debate started last April, and it was what senators were debating as the clock ran out on the regular session in June. Haley unsuccessfully tried to force legislators back to Columbia. While she named three other restructuring bills she wanted legislators to deal with, she made clear that her top priority in the order was the Department of Administration bill.

The state’s high court ruled that Haley’s order calling lawmakers back into session during their break violated the separation of powers.