President Obama delivers remarks at the Department of Homeland Security on his fiscal year 2016 budget proposal, on Monday, Feb. 2, 2015, in Washington. (Evan Vucci/AP)

President Obama’s $4 trillion budget would do a lot of things, but one of the most controversial may turn out to be allowing legal sales of marijuana in the nation’s capital.

D.C. voters overwhelmingly approved a ballot measure last year to follow Colorado and Washington state in legalizing pot for recreational use.

But in December, outgoing Democrats and incoming Republican leaders in Congress moved to halt the measure. Under a broad budget deal, they prevented the District’s mayor and council from spending any money to work out the specifics of how pot would be sold, which the ballot measure left up to local politicians to decide.

The congressional interference left in limbo the fate of the entire legalization measure, which was approved by 7 in 10 D.C. voters.

Obama’s budget, however, would remove the congressional restriction, allowing D.C. leaders to spend the city’s tax money to develop a regulatory scheme and system for taxing pot sales. If allowed by Congress, that could let pot stores open in the nation’s capital as early as the end of the year.

President Obama’s annual budget proposal includes a $4 trillion price tag, a 10-year deficit reduction plan — and almost no chance of passing a Republican-controlled Congress. Here’s what you need to know about his proposal and its political implications. (Julie Percha/The Washington Post)

The tiny two-word change — tucked on Page 1,248 of Obama’s budget — was first noticed on Monday by Tom Angell, chairman of the Marijuana Majority.

“It’s great to see the president taking this subtle but important action to clear the way for the District to sensibly regulate marijuana,” Angell told The Washington Post. “Now it remains to be seen whether leaders in Congress will stand with the majority of the American people or if they’ll do everything they can to protect failed prohibition policies.”

D.C. Council Chairman Phil Mendelson last month challenged Congress to either block the ballot measure or let it stand, saying that by March the city would begin treating the ballot measure as law — that would effectively legalize possession without any legal way to purchase the drug.

Mendelson sent the ballot measure — known as Initiative 71 — to Capitol Hill, starting the clock ticking on a 30-day review that Congress has used just three times in 40 years to quash a local D.C. law.

House conservatives played down Mendelson’s challenge, saying they didn’t need to act because the city’s marijuana measure was suspended already through the December budget deal. Rep. Andy Harris (R-Md.) has warned that the District will be in violation of Congress if it moves forward.

D.C.’s new mayor, Muriel E. Bowser, has also said she worries that legalizing the drug without any legal means for purchasing it could lead to open-air drug markets. But she has said she would rather move forward with the risky step than stand in the way of the will of city voters as Congress has done.

Initiative 71 would allow residents and visitors ages 21 and older to legally possess as much as two ounces of marijuana and would allow residents to grow up to three mature marijuana plants each at home.

After Republicans’ first weeks in power in Congress, it appears clear that fighting legalized pot is far down the party’s list of national priorities.

But Obama’s budget will have to pass through committees in both congressional chambers stacked with conservatives. It would be relatively easy for Harris, a member of the House Appropriations Committee, to again amend Obama’s budget in committee and strip out the allowance for D.C. to legalize marijuana.

The congressional interference on marijuana has become the most high-profile example in years of the District’s lack of autonomy from Congress.

The District has a population larger than the states of Vermont or Wyoming but no voting representation in Congress. Despite over $7 billion in local tax revenue, all of its spending decisions with that money are subject to being overridden by Congress through the federal budget process.

Marijuana legalization has also become a flash point with Congress because strict federal laws on cannabis have become intertwined with discussions of racial justice.

Many D.C. voters supported legalization last year, saying they had been moved by studies that showed the District’s marijuana-arrest rate was higher than any of the 50 states and ranked seventh nationally among a study of 1,000 counties analyzed by the American Civil Liberties Union.

Nine in 10 arrests were also of minorities.

The D.C. Council last year did strip away jail time for possession and made the penalty a $25 fine — cheaper than most city parking tickets.

On the District’s iconic federal land, including the Mall, the monuments and streets surrounding the White House, possession remains a federal offense punishable by up to a year in jail.