JEFFERSON CITY, Mo. — Gov. Jay Nixon has vetoed money for the Missouri Department of Transportation in retaliation for a publicly financed lobbying effort against a bill relaxing Missouri’s motorcycle helmet mandate.

The department recently spent about $33,000 on a public opinion poll showing that a majority of respondents favor an existing state law requiring all motorcycle riders to wear helmets.

Department director Pete Rahn cited the poll during a news conference outside a hospital emergency room last month while urging Nixon to veto a bill allowing people age 21 and older to ride helmet-free on all Missouri roads except interstate highways.

On Thursday, Nixon vetoed $33,000 from the transportation department’s administrative budget for expenses and equipment during the fiscal year that starts Wednesday. The Democratic governor said in a written veto message that the cut was “due to administrative inefficiencies.”

Nixon spokesman Jack Cardetti confirmed Friday that the veto was in response to the poll on the motorcycle helmet law, which was funded from Missouri’s share of federal highway safety money.

“The governor thought that political polling was a waste of taxpayers’ dollars and therefor he took it out of their administrative budget for next year,” Cardetti said.

Transportation department spokeswoman Sally Oxenhandler said Friday that agency officials “have no response at this point” to Nixon’s veto.

Nixon has until mid-July to decide whether to sign or veto the motorcycle helmet legislation.

The governor’s office has been inundated with e-mails from motorcyclists urging him to sign the legislation. Those e-mails, obtained by The Associated Press under the open-records law, include several in which the authors describe assurances by Nixon that he will sign it.

In an interview with the AP last month, Nixon denounced the poll, declaring: “Taxpayers are darn sick and tired of people spending public money to lobby public officials like that.”

Rahn has defended the poll as part of the department’s mission to promote highway safety, asserting that more motorcyclists would be killed and injured if Missouri’s helmet law is relaxed.

After the line-item veto, the department still is budgeted to receive more than $27 million from state road funds for administrative expenses, equipment and personnel.