WASHINGTON -- Congress could soon wade into an issue perplexing states: How many days of opioid painkillers, which are highly addictive, should be prescribed at a time?

Sen. Rob Portman of Ohio and a group of seven colleagues on Tuesday proposed making it three days. If a patient needed a painkiller for a broken arm or a pulled wisdom tooth, he could get a prescription for no more than three days worth of opioids under a law Portman and colleagues proposed. If the patient needed more, he'd have to persuade the doctor a few days later.

This is a shorter span than mandated in most states that have any mandates at all. Kentucky adopted a three-day opioid-prescription rule last summer, but Ohio Gov, John Kasich chose seven days for his state. New Jersey last year limited initial opioid prescriptions to five days.

California, West Virginia and Florida have been debating about their own proposed three-day limits.

CVS meantime said that starting this month, it would limit most opioid prescriptions to seven days.

A federal law could settle this for everyone. But how strict those limits might be is far from settled. Nearly a year ago, Sen. John McCain, an Arizona Republican, and Kirsten Gillibrand, a New York Democrat, proposed making it seven days.

Lawmakers say a federal requirement is needed because opioid painkillers such as OxyContin are considered a gateway to addiction that can lead to dependence on heroin and the synthetic drug fentanyl, deadly opioids that have put the nation in the grip of a crisis. The number of painkiller prescriptions has dropped amid awareness of the problem -- and amid lawsuits from states against drug companies for promoting and shipping the drugs while knowing of addiction risks -- but there are still too many, lawmakers say.

Patients with chronic pain and certain conditions such as cancer could get opioids for longer periods under the three-day proposal, unveiled Tuesday as part of a new opioid legislative package. The bill would include $1 billion in additional federal funding for programs to treat opioid addiction and recovery and give first responders better access to naxolone, used to reverse the effects of overdoses.

The bill seeks to build on legislation and funding passed in late 2016, the Comprehensive Addiction and Recovery Act, or CARA, that was hailed for its sweeping nature. But with $267 million in funding for the last fiscal year, CARA was recognized as inadequate to address the nation's ongoing opioid epidemic.

"Now we have the opportunity to build on this effort, increasing funding levels for programs we know work and implementing additional policy reforms that will make a real difference in combating this epidemic," Portman, an Ohio Republican and an original CARA backer, said.

President Donald Trump's latest budget proposal has also called for greater funding to fight the opioid epidemic, as did a recent budget agreement in Congress. The bill introduction Tuesday could drive the legislative mechanisms needed for those goals.

It was introduced by Portman and Sens. Sheldon Whitehouse, Democrat of Rhode Island; Shelley Moore Capito, Republican of West Virginia; Amy Klobuchar, Democrat of Minnesota; Dan Sullivan, Republican of Alaska; Maggie Hassan, Democrat of New Hampshire; Bill Cassidy, Republican of Louisiana, and Maria Cantwell, Democrat of Washington.

Why three days as the limit for prescriptions for acute pain?

That's the amount recommended by the Centers for Disease Control and Prevention, which says way too many addictive pain pills are in circulation. In 2015, the CDC said, enough opioids were prescribed to medicate every American around the clock for three weeks.

For patients in acute pain, three days or fewer is often enough, the CDC says.

This has led to worry in states about doctors and pharmacies being backed up with patients every four days. The debate has been acute in Florida, where doctors recently warned such a rule would be too rigid on practitioners and burden patients with prescription renewals.

But the CDC has said more than seven days of opioid relief is rarely needed for acute pain.

The new bill is far from passage and is likely to prompt congressional hearings that bring in pain experts, pharmacists and medical groups for discussion.