Oklahoma U.S. Sen. James Lankford said he is still working on a resolution for 800,000 undocumented immigrants covered by the policy known as DACA.

Lankford said the Senate was hearing legislation earlier this year to give them a pathway to citizenship before President Trump ended the Obama-era program, subjecting them to deportation, but those bills fell victim to timing.

"At the same time, federal courts were stepping in and saying to the president, ‘We’re going to put this, any changes, on hold until we review this.’ As soon as the courts did that, a bunch of the members of the Senate just walked away and said, ‘Never mind. There’s no deadline anymore. Never mind, we’ll do this some other time,’ with an unnamed ‘some other time,’" Lankford said.

Lankford said many lawmakers also turned their attention to gun control after the school shooting in Parkland, Florida.

Lankford said any DACA resolution must come in tandem with border security measures, largely because of increased activity by Mexican drug cartels.

"Ten years ago, the cartels in Mexico were buying all of their heroin from Afghanistan, actually, the top producer of poppies in the world. So, then they started planting poppies in the mountain areas of Mexico and now they’re producing their own heroin," Lankford said, adding cartels are now making their own fentanyl, too.

They used to get the powerful and potentially deadly narcotic often cut into heroin from China.