The Drug Enforcement Administration on Thursday rejected calls to relax a nearly five decade-classification of marijuana as a dangerous drug on par with heroin and ecstasy, dealing a blow to pro-legalization advocates and the budding pot industry.

The DEA, in making its long-awaited announcement, said the decision to keep marijuana as a "Schedule 1" narcotic “is tethered to the science.”

“Right now, the science doesn’t support [the reclassification],” Chuck Rosenberg, acting DEA administrator, said.

In a separate interview with National Public Radio, Rosenberg said the decision “isn’t based on danger” but rather on “whether marijuana, as determined by the FDA, is a safe and effective medicine. And it’s not.”

The government’s decision was announced in the Federal Register. Despite the punt on pot, the DEA did agree to open the door to more medical research on cannabis and its effects.

Currently, marijuana is classified as a “Schedule 1” drug with no “accepted medical use and a high potential for abuse.” That puts it in the same category as ecstasy and gamma-hydroxybutyrate, known commonly as the “date rape” drug.

The decision to keep that classification continues the widening disconnect between state and federal policy.

Twenty-five states have taken matters into their own hands -- sanctioning some form of the plant for medical purposes.

Colorado, Alaska, Washington, Oregon and the District of Columbia have taken it a step further, legalizing its recreational use. And in November, a handful of other states including California, Nevada, Arizona, Massachusetts and Maine, will have recreational or medical marijuana proposals on their ballots.

California Republican Rep. Dana Rohrabacher condemned the DEA’s decision, saying it “shows the disconnect between the Obama administration and the common sense of the American people.”

“The government’s continued allocation of resources and controls with the intent of trying to prevent the adult use of marijuana has been counterproductive and an indefensible limitation of people’s right to control their own lives,” Rohrabacher said in a written statement. “The Obama administration has had the chance to correct a foolish and counterproductive policy. Now it’s up to the Congress and the next administration.”

Rohrabacher co-sponsored legislation with Rep. Sam Farr, D-Calif., that prohibits the Justice Department from using funds to prosecute medical marijuana cases in states where it’s legal.

The federal government has rejected multiple appeals in the past to reclassify marijuana, arguing that its negatives outweigh potential benefits.

“It’s outrageous that federal policy has blocked science or so long,” Rep. Earl Blumenauer, D-Ore., said in a written statement following Thursday’s announcement.

The DEA did indicate it would allow researchers and drug companies to use marijuana grown in other places. Currently, it’s cultivated only at a facility at the University of Mississippi. Increasing the supply and the variety of marijuana made available for scientists seeking to study particular strains of the drug was widely seen as a consolation prize.

While Blumenauer praised the promise of more marijuana research, he maintained the government’s decision doesn’t go far enough and that the DEA “doesn’t get it.”

“Keeping marijuana at Schedule I continues an outdated, failed approach – leaving patients and marijuana businesses trapped between state and federal laws,” he said. “This decision does not address other key concerns like the need for banking services and tax equity for small businesses, operating legally in half the states. It’s not right or fair.”

Some medical professionals like Carl L. Hart, a professor of psychiatry at Columbia University, say changing marijuana’s classification to a “Schedule II” drug would have “represented a major step toward resolving the hypocritical mess that characterizes our current laws on marijuana.”

Hart, who has studied the drug for decades and has had to jump through numerous regulatory and bureaucratic hoops, says the DEA’s punt strips credibility from scientists and researchers who study the drug for medical purposes.

“It’s time we lessened the outside influence of a law enforcement agency on medical decisions and started to rebuild our credibility as scientists on the marijuana issue,” he wrote in Scientific American.

Stuart Titus, CEO of Medical Marijuana, Inc., told FoxNews.com that while Thursday’s DEA decision is a step in the wrong direction, he is optimistic that in the future there will be “a change of mind and a change of attitude.”