NASHVILLE (AP) — A former top Drug Enforcement Administration official says he told staffers who work with Tennessee Rep. Marsha Blackburn exactly what to expect from a 2016 law she co-sponsored during the nation's opioid crisis.

He ripped into her later suggestion the law may have had "unintended consequences."

Joe Rannazzisi, former head of DEA's Office of Diversion Control, said in an interview with The Associated Press that he told the congressional staffers during a July 2014 conference call that the bill would hamper the DEA's ability to go after companies illicitly distributing opioids.

Rannazzisi made the comments in the homestretch of Republican Blackburn's heated Senate race against former Democratic Gov. Phil Bredesen. Both sides have spent millions of dollars on ads targeting the opioid epidemic.

The scourge killed Tennesseans at a rate of 18.1 out of every 100,000 people in 2016, the 14th highest among states and Washington D.C.

The law that Blackburn co-sponsored increased the burden for DEA to immediately suspend large shipments of drugs, requiring that it demonstrate a "substantial likelihood of an immediate threat that death, serious bodily harm, or abuse of a controlled substance will occur" without action. Congress passed the law unanimously and then-President Barack Obama signed it.

Amid campaign trail criticisms, Blackburn co-sponsored legislation last month to ease that law and require "probable cause to believe an imminent threat that death, serious bodily harm, abuse, or diversion" will occur. The bill hasn't moved yet. Before the 2016 law, a finding of "imminent danger to the public health or safety" was only required.

Rannazzisi was a whistleblower in an October 2017 report on the law by The Washington Post and CBS' "60 Minutes." After his concerns aired, the measure's chief sponsor, Republican Rep. Tom Marino of Pennsylvania, withdrew as President Donald Trump's drug czar nominee.

Following the report, a Blackburn spokesman released a statement saying if the law had "any unintended consequences," they should be addressed immediately.

Rannazzisi, however, says backers of the 2016 law, which "made a mark on enforcement for many years to come," had been warned about what would happen.

"The (U.S. House) Energy and Commerce and Judiciary staffs, and individual staffers from individual congressmen were on that phone call," Rannazzisi said. "So, for (Blackburn) to say she didn't know, or those were unintended consequences, that's nonsense because I told them what the consequences would be. I explained to them what the consequences of that bill would be way back in July of '14."

Asked about Rannazzisi's recent comments, Blackburn campaign spokeswoman Abbi Sigler said the congresswoman is working toward a "systemic solution" to the opioid epidemic while Democrats "point fingers and politicize a public health crisis."

Bredesen, meanwhile, has called for the law's repeal and freely criticizes the pharmaceutical industry on the campaign trail. But a group tied to GOP Senate Majority Leader Mitch McConnell has fired back.

The Senate Leadership Fund ad says Bredesen holds up to $1 million in Johnson & Johnson stock, and the company and its subsidiaries have faced lawsuits over its opioids. The Senate Leadership Fund said it was spending $1.8 million on that ad and $13.6 million in Tennessee total to date.

Tennessee had five opioid-related deaths per 100,000 people when Bredesen became governor in 2003, compared to 4.5 nationally, according to data from the U.S. Centers for Disease Control and Prevention. The Tennessee death rate grew to 10.1 in 2011, when Bredesen left office, compared to 7.3 nationally, the data show.

Bredesen would be one of the wealthiest members of Congress if elected. He has said his extensive list of investments is sensible, realistic and has "nothing weird in there." In 2002, when Bredesen was running for governor, he reported investments of at least $250,000 in 71 companies, including Johnson & Johnson.

Bredesen's campaign called the attack the "kind of muck that Tennesseans hate from DC."

Blackburn took to TV to say she's working with both parties to solve the crisis, seeking "$1 billion in new funding, new treatment options for veterans, and tough criminal penalties on drug makers who flood Tennessee with pills."

But Bredesen featured retired DEA investigator Jim Geldhof in another spot attacking Blackburn on the legislation she co-sponsored.

The issue offers Democrats a less partisan line of attack in the red state, where Blackburn has linked Bredesen to national Democrats at every turn, criticizing his opposition to Trump's proposed U.S.-Mexico border wall and tax cuts.

Majority Forward, a political group aligned with Democratic Senate Minority Leader Chuck Schumer, has led the attacks on Blackburn, the DEA law and her pharmaceutical industry campaign contributions. The group has spent more than $10.1 million in Tennessee, including at least six ads attacking Blackburn on opioids.

Rannazzisi and Blackburn have sparred previously about the law.

They engaged in a testy back and forth in an April 2014 House panel hearing about the bill.

Five months later, Blackburn and Marino sent a letter requesting an Office of Inspector General investigation into Rannazzisi, saying he tried to intimidate Congress in the July conversation. Rannazzisi said he was removed from his post in August 2015 and now works with state attorneys general suing the industry over opioids.

Blackburn has said the DEA missed its deadline to report to Congress in April 2017 about whether the law wasn't working. Then in February, the Justice Department suggested changing to a "probable cause" standard, which Blackburn's co-sponsored bill includes.

Blackburn has expressed support for provisions such as a three-day federal opioid prescription limit, with exceptions for cancer and hospice treatment.

Rannazzisi said her focus should be on repealing the 2016 law.

"After the fact now, after you've been exposed, you now say, 'Well, I've done this and that,' do the public a favor," Rannazzisi said. "If you want to do something, repeal the bill that got this all started."