Marijuana legalization soared to victory in Washington, DC, on Tuesday when nearly 70 percent of the city's voters approved Initiative 71. But before the measure becomes law, it faces a hurdle that could prove difficult to overcome: Congress.

Since DC is the nation's capital and a federal jurisdiction, Congress has the final say over its laws. Initiative 71 in particular faces a 30-day congressional review period. Federal lawmakers could pass a resolution during this time period rejecting the law, or they could take no action and let the law take effect by doing nothing. There are also more roundabout ways to potentially kill legalization, such as through a budget measure (Congress also approves DC's budget).

But will the federal government actually block DC's law? Maybe not, explained Kimberly Perry of DC Vote, an organization that campaigns for DC statehood.

"I'm not for having the federal government get involved"

The resolution would need to work through the House and Senate, then get President Barack Obama's signature. The White House has been unwilling to get involved in DC's affairs in the past. It also seems unlikely a resolution would be able to work through the House and Senate, even with both chambers under Republican control.

Chris Meekins, spokesperson for Rep. Andy Harris (R-MD), who in June led an unsuccessful effort to block DC's marijuana decriminalization law, said Harris is considering any options to block DC's legalization measure. "Increasing teenage drug use is not something that's in the best interest of the federal government, particularly in our capital city," Meekins said. (So far, there's no evidence that legalization, either medical or recreational, leads to increased drug use among teens.)

But Sen. Rand Paul (R-KY), who's poised to take over the Senate subcommittee that oversees DC, told Roll Call that he won't block Initiative 71. "I'm not for having the federal government get involved," Paul said. "I haven't really taken a stand on [legalization in DC], but I’m against the federal government telling them they can't."

So if a resolution makes it through the House, it seems unlikely to make it through the Senate. Initiative 71 appears to be safe — for now.

Correction: An earlier version of this story claimed the congressional period could last 60 days, based on information from interviews and other media reports. The review period is actually 30 days, since Initiative 71 doesn't directly alter certain sections of DC law that would trigger a 60-day review.