When President Obama won the White House in 2008, few groups had more more hope for change than proponents of medical marijuana, the dispensaries allowed to sell pot under some state laws, and the cancer, HIV/AIDS, and other patients who benefit from the drug. And in the first two years of Obama's term, things looked pretty good for the medical marijuana industry: Attorney General Eric Holder told federal prosecutors to lay off individuals complying with state laws, and they did. Then the hammer came down, and now, the Obama administration is "cracking down on medical marijuana dispensaries and growers just as harshly as the administration of George W. Bush did," says Michael Scherer at TIME. What happened? Here, three theories:

1. Obama doesn't want to look soft on crime

The most plausible explanation for Obama's about-face is that he became "worried about Republican accusations that he is 'soft on drugs,'" says Jacob Sullum at Reason. That's an old (and baseless) GOP line of attack, but Obama probably "thought himself especially vulnerable to such criticism" given his own youthful drug use and the rapid proliferation of large medical marijuana dispensaries under his relaxed watch. And since U.S. attorneys were never really on board with his soft touch, it was easy to just "let the drug warriors in the Justice Department do what drug warriors do."

2. He doesn't think potheads vote

Comedian Jimmy Kimmel nailed it at the White House Correspondents' Dinner when he needled Obama for the crackdown on weed and pointed out, "You know, pot smokers vote, too," says Chris Weigant at The Huffington Post. But it was his punchline — "Sometimes a week after the election, but they vote" — that describes the White House mentality: We can alienate the "marijuana vote" at no cost. But Team Obama is wrong. The pro-weed voting bloc is big, it's diverse, and now it's mad. It's also worth noting, says Rob Kampia in California's Monterey County Herald, that legalizing medical marijuana polls in the high 70s, making it "far more popular than Obama."

3. States pushed too far, leaving Obama little choice

It's so easy to score medicinal pot in states like California and Colorado that they've "effectively legalized the drug for recreational use," says Andrew Sullivan at The Daily Beast. This "abuse of medical marijuana laws" certainly weakened Obama's ability to keep the Drug Enforcement Administration at heel. I wish the DEA would stand down, but "I also wish some states had exercized more discretion and care in allowing for medical marijuana." Indeed, the bottom line is that "federal prosecutors have lost faith in the ability of state and local officials to control a booming commercial industry for a drug that is still illegal to grow, possess, or sell under federal law," says TIME's Scherer.