By Harriet McLeod

CHARLESTON, South Carolina (Reuters) - The Republican leader of the South Carolina Senate filed suit on Monday to challenge Republican Governor Nikki Haley's executive order for lawmakers to return to work.

The legislature ended its regular session last Thursday and scheduled an extra session to start June 14 in order to finish work on the budget and other issues.

But the governor immediately ordered them to come back into session starting Tuesday without pay to complete work on her legislative agenda.

Saying Haley can't do that without extraordinary circumstances, Senate President Pro Tempore Glenn McConnell asked the state Supreme Court to intervene.

"My job is to defend the South Carolina Constitution, to follow the rules of the Senate and to uphold the law," said McConnell, a Republican from Charleston.

"Simply because the governor and I want certain bills enacted does not give us the power to ignore the constitution."

Haley said last week that she wants lawmakers to restructure state government and finish work on their illegal immigration bill, among other things.

"If the energy invested in avoiding coming back to work would instead go into passing these important restructuring reforms, South Carolina would be far better served," Haley spokesman Rob Godfrey said Monday.

The state House of Representatives had planned to return next week to finish drawing a new voting district but will follow the governor's order to come back sooner, said Greg Foster, spokesman for House Speaker Bobby Harrell.

"The governor can only call us back to work. She cannot dictate what we take up or how long we stay in," Foster said.

(Editing by Colleen Jenkins and Greg McCune)