SPRINGFIELD, Ill. — A proposal aimed at delaying the effects of helmet-banging head trauma by banning Illinois children younger than 12 from playing tackle football lacks the votes this spring, its sponsor said Wednesday.

Rep. Carol Sente said parents and taxpayers “need more time to absorb the evidence” of a link between repeated blows to the brain and chronic traumatic encephalopathy, a dementia-like, degenerative disease characterized by memory loss, violent urges, depression and other cognitive troubles.

Opposition to restrictions on America’s most popular sport stifled it for now. Sente, a Vernon Hills Democrat, said she will not call the legislation for a House vote before the General Assembly’s scheduled May 31 adjournment. But the bill stays alive until year’s end, and Sente, who is not seeking re-election in November, raised the possibility that the issue might be ripe for a vote this fall.

“This is cutting-edge research that is evolving weekly,” Sente said. “As the evidence reaches parents, I believe more individuals will delay when their child starts playing tackle football. If they don’t have options like flag football, I believe in time parents and youth will steer away from football entirely.”

Legislation similar to Sente’s is in play this spring in New York, New Jersey, and California. Last month, a Maryland House committee voted down a prohibition on tackling before age 14.

Sente’s plan is named for former Chicago Bears defensive back Dave Duerson, who took his own life at age 50 in 2011 but preserved his brain for research that ultimately revealed the markers of CTE, which can only be confirmed after death.

The medical journal JAMA reported last summer than CTE was found in 110 of 111 brains of former NFL players whose brains were donated for research.

CTE is often associated with concussions, but experts contend the real danger is from the thousands of hits that a football player sustains throughout a season.