"I've talked to people all over the country about marijuana," said Corey Barnette, a principal at District Growers, the cultivation facility that will service the center. "Everyone is highly focused on what happens in Washington, D.C. We are a city on top of the feds, and with Congress right here. If we can make it work, it can work anywhere."

Last year, Polis's home state of Colorado, along with the state of Washington, became the first states to legalize marijuana for recreational use. Places around the country have been loosening their laws, and just this week Maryland voted to decriminalize small amounts of weed.

But, regardless of what individual states do, the use or cultivation of marijuana remains a federal crime under the Controlled Substance Act. This means that even if state law enforcement allows for use of the drug, federal officials do not. In the eyes of the federal government, there is no such thing as "medical marijuana."

This is where Polis and Blumenauer come in. The duo has dropped a series of bills to end the federal prohibition on the drug, impose federal tax on sale of legal pot, and protect the rights of patients using medical marijuana. At this point, especially in a Republican-run House of Representatives, these bills have an upward climb toward becoming law. But the way things have been shifting, that could change rapidly.

In this sense, the congressmen and the dispensary can help each other out. District pot sellers need the protection of a federal law, and the congressmen could use a place to show to their skeptical colleagues what it really looks like and its impact on a community.

While Congress may be filled with skeptics, marijuana has surged in popularity around the country. In the 1980s, only about 30 percent of Americans thought marijuana should be legal. By 2011, half of Americans thought it should be legalized. Today, 70 percent of Americans think doctors should be able to prescribe marijuana to alleviate pain and suffering. Advocates hope that a dispensary right in the nation's capital could be a watershed moment in the marijuana-reform movement.

"It's a very different discussion when you talk with members who have medical or legal sale of marijuana in their district versus those who don't," Polis told National Journal in an interview later at the Capitol. "It's extremely hypothetical for members who have never seen a dispensary. This can bring it a little closer to them by letting them know how it really works."

This responsibility is not lost on anyone. Perhaps that's why there are still no dispensaries operating in the District, even though it's been 14 years since the city voted to legalize medical marijuana. Most of the wait can be blamed on Congress, which blocked funding for the program until 2009. The rest of the time can be chalked up to a burdensome regulatory process that advocates say will make the District's one of the most restrictive programs in the country: You can't grow where you sell; there can only be five dispensaries and a maximum of 10 growing centers in the city; growers can only grow a maximum of 95 plants; and only D.C. residents are eligible to purchase. And yet, even those who adhere to these regulations have plenty of cause for concern.