Congress will now have to decide if it wants to try to block a marijuana decriminalization measure signed Monday by D.C. Mayor Vincent Gray (D).

After the D.C. Council approved the measure earlier this month, some conservatives on Capitol Hill warned the changes would have negative effects on both the economy and public health in the nation's capital. But GOP leaders — including those on the House Oversight and Government Reform Committee, which has jurisdiction over the D.C. government — were noncommittal about their next move.

Under the bill, smoking pot in public would remain a jailable criminal offense. But those found carrying small amounts of the drug, or smoking it in the privacy of their homes, would face civil penalties of just $25 in lieu of criminal charges.

With the change, D.C. moves closer to legalizing marijuana for recreational use, as Colorado and Washington state have already done. More than 20 states, as well as the District, have legalized the drug for medical use.

After the bill's Council passage, Oversight Committee Chairman Darrell Issa (R-Calif.) said that he was talking to council members and still weighing his options, while House Speaker John Boehner (R-Ohio) was equally as vague.

"I really haven't seen what the D.C. Council did, but I'm sure we'll look at it," Boehner told reporters at the time.

Under the unique rules governing the District of Columbia, Congress will have 60 days to reject the proposal before it takes effect.

Such a move is extremely rare, as it requires the House, the Senate and the White House to be in agreement. But some Democrats on the Oversight Committee are expecting at least some push-back from Republicans on the panel.

Rep. James LankfordJames Paul LankfordHillicon Valley: Verizon, AT&T call off data partnerships after pressure | Tech speaks out against Trump family separation policy | T-Mobile, Sprint make case for B merger 13 GOP senators ask administration to pause separation of immigrant families Senators introduce bipartisan bill to detect supply chain risks posing threats to national security MORE (R-Okla.) is one such critic. A member of the Oversight Committee who also chairs the Republican Policy Committee, Lankford said he fears the impacts the looser restrictions will have on economic output in D.C.  

"I don't think it helps productivity in a community," Lankford said after the D.C. Council vote. "Decriminalizing it … I don't think that sends the right message to the next generation or the current working generation."