The House blocked a plan to bar seasonal employees such as bus drivers from receiving unemployment benefits over the summer.

The measure was added in the Senate to House Bill 361, which began life as a bill to allow many workers to opt out at any time from automatic payroll deductions for union dues. Speaker David Ralston, R-Blue Ridge, ruled Thursday that the Senate amendment violated the constitutional requirement that any bill deal only with one topic.

The bill now goes back to the Senate in its original form.

The ban on jobless benefits in the bill would affect seasonally unemployed bus drivers and other private-sector workers whose employers contract with public-sector entities such as school systems. Supporters said it would save the state up to $10 million annually.

Georgia Labor Commissioner Mark Butler made a similar ruling last year, defying a federal mandate by refusing to restart jobless benefits to seasonally unemployed bus drivers who work for private contractors. Federal labor officials have yet to respond to that action.

The state’s financially struggling unemployment insurance fund has sought to cut spending and reduce its jobless roll — estimated at 423,337 as of January. Georgia owes Washington roughly $740 million for jobless assistance borrowed during the recession.