Washington Hospital Center nurses, also organized by National Nurses United, engaged in a brief strike in 2011. (Mark Gail/The Washington Post)

Registered nurses at Providence Hospital voted to unionize Tuesday, continuing a wave of organizing among D.C. nurses as health-care industry uncertainties trickle down to rank-and-file employees.

Providence becomes the seventh D.C. hospital to have nurses organized under the banner of National Nurses United, a nationwide federation of nursing unions. Bringing Providence’s roughly 400 RNs into the fold, organizers hope, will also help push forward D.C. Council legislation mandating certain nurse staffing levels in city hospitals — legislation that is now languishing amid fierce lobbying from hospitals who argue that such “staffing ratios” increase costs without improving patient care.

Carl Ginsburg, a spokesman for National Nurses United, said he expected the staffing bill to get “greater consideration” from lawmakers in light of the union vote, which passed 232 to 66. “Nurses from Providence have already testified about staffing shortcomings, pronounced staffing shortcomings,” he said, jeopardizing patient care. “They have been forthright in their demand that a new safe staffing law be passed in the District.”

But with several key D.C. Council members opposed to the bill — including, crucially, Health Committee Chairwoman Yvette M. Alexander — there is little immediate prospect for it to become law.

NNU-organized nurses have had contentious contract negotiations, particularly at MedStar Washington Hospital Center, the city’s largest acute care hospital, where nurses walked off the job for a brief strike in 2011. Meanwhile, at Providence, one of the District’s smallest acute-care hospitals, a top executive said she was hopeful the organizing effort will have little outward effect.

“We’ll continue to serve our community and serve all of our patients, with special attention to those who are poor or vulnerable,” said Senior Vice President Karol Marciano. “There will be no change to any of our strategic plans.”

Nor, Marciano said, will there be significant changes to the hospital’s staffing model. But she said she understood the impulses behind the organizing effort: “I think it has everything to do with the challenges we’re facing these days. … All of health care and the delivery aspects of health care are changing. Those changes can drive changes in the way you structure your workforce.”