The Associated Press reports that federal officials are beginning a California-style crackdown on medical marijuana businesses in Colorado.

As CBS4 originally reported in December when rumors of crackdown were beginning to take shape, the crackdown will be focused on medical marijuana businesses that are within 1,000 feet of schools. They must shut down within 45 days or face federal penalties.

Letters were sent out to 23 medical marijuana businesses in Colorado on Thursday, according to The Denver Post. This is the most aggressive law-enforcement action that the federal government has pursued in the state.

The reasoning behind the 1,000 foot boundary stems from federal law which uses that measurement as a factor in drug crime sentencing. There are many dispensaries in Colorado that are within 1,000 feet of schools, according to High Times, because they were approved by local laws to do so. However, the federal law trumps the state law.

This comes after a December poll released by Public Policy Polling showing that a large group of Coloradans believe that marijuana should not just be legal medically, but fully legalized. From the Public Policy report:

Coloradans are even more strongly in favor of legalizing marijuana, and they overwhelmingly believe it at least should be available for medical purposes. 49% think marijuana use should generally be legal, and 40% illegal. But explicitly for medical use, that rises to a 68-25 spread. Just five years ago, a referendum to legalize simple possession by people over 21 failed by 20 points. On the medical question, Democratic support rises from 64% for general use to 78%; Republicans rise from 30% to 50%, and independents from 54% to 75%.

The Colorado Independent reports that the Public Policy Polling data "flies in the face of statements made by a number of legislators over the past year that if voters knew what they were in for, they would never have approved medical marijuana in the first place." Art Way, Colorado manager for the Drug Policy Alliance, went even further telling the Independent that, "decision-makers and elected officials really just don't have the pulse of the people they represent. The average person considers the federal position that marijuana has 'no medical value' to be a joke."

Rep. Jared Polis (D-Colo.) echoed a similar sentiment when he told HuffPost back in Nov. 2011:

There are more pressing issues facing federal law enforcement so it makes no sense for them to waste time and taxpayer money interfering with state-legal businesses that voters have approved, that are well-regulated, and that generate jobs and economic activity. Colorado has the nation’s strictest regulatory system, which means our dispensaries operate transparently and legitimately. I should hope that the federal government would focus its resources on keeping Americans safe from crime rather than interfering with a legal business that benefits Colorado’s economy.

The crackdown comes less than 10 days after the Campaign To Regulate Marijuana Like Alcohol, a collective of marijuana activist groups and individuals including SAFER, Sensible Colorado, NORML and others gathered more than double the required signatures for an initiative to end marijuana prohibition in Colorado to appear on the 2012 state ballot.

The Regulate Marijuana Like Alcohol Act of 2012 would make the personal use, possession and limited home-growing of marijuana legal for adults aged 21 and older. It establishes a system in which marijuana is regulated and taxed similarly to alcohol is currently. The act also would allow for the cultivation, procesing, and sale of industrial hemp.

Read the entire Regulate Marijuana Like Alchool Act of 2012 here.