ST. LOUIS — Seeking a Midwest version of the famed Boston Tea Party, Illinois’ second-highest politician wants residents to mail tea bags to that state’s two biggest electric utilities in protest of coming rate hikes.

The U.S. Postal Service on Wednesday offered a caveat: Skip the tea.

Saying full tea bags could be bulky enough to harm its equipment and create security scares by leaking brown residue, the Postal Service says consumers can get their point across by tucking an empty tea bag inside their monthly bill to ComEd or Ameren Corp.

“It’s absolutely legal for people to mail a tea bag,” said David Colen, a postal inspector and spokesman for the Chicago division of the U.S. Postal Inspection Service, a law-enforcement arm of the agency. “By no means are we trying to stop what the lieutenant governor is trying to do. We just want to keep the mail flowing.”

On Tuesday, Illinois Lt. Gov. Pat Quinn pressed his bid to get ComEd or Ameren customers to include a tea bag with their monthly payments, likening the effort to Boston’s 1773 protest in which colonists dumped tea into the Boston Harbor to object to unfair taxation by the British.

Quinn’s campaign comes before the first electricity rate increase for Illinoisans in a decade.

Utility officials announced last Friday that rates will jump on average between 22 percent and 55 percent next year following the state’s first public energy auction. Wholesale rates determined by the auction will mean preliminary average increases of about $13 a month for ComEd customers and between $26 and $33 a month for Ameren customers.

ComEd, a division of Exelon Corp., serves 3.7 million customers across northern Illinois, while St. Louis-based Ameren serves 1.2 million customers in southern and central Illinois.

Quinn stoked his request for the tea bags during news conferences this week in Chicago – home to ComEd – and outside Ameren’s St. Louis headquarters, calling the rate increases “arrogant unfairness.”

Quinn spokeswoman Elizabeth Austin said consumers reluctant to mail in tea bags may mail a computer image of one that’s on Quinn’s official Web site.

Valerie Hughes, a spokeswoman for the Postal Service’s St. Louis operations, said as of Wednesday there were no reports that tea bags caused any mailing problems.