Tanya Snyder holds Milo Evans-Snyder, 5 months old, left, Jessica Champagne holds Benjamin Toth-Champagne, 3 months old, center, and Jamie Davis Smith holds Adam Smith, 10 months old, right, after dozens of parents with toddlers and people sat through a D.C. Council hearing in October, 2015 on paid family leave. (Jabin Botsford/The Washington Post)

D.C. Council members voted Tuesday to move forward with one of the nation’s most generous laws guaranteeing family and medical leave, creating roughly $250 million a year in new taxes on local businesses to fund two months of paid time off for workers to care for newborn or adopted children.

The bill, which would apply to both full- and part-time workers, also grants employees six weeks of paid leave to help ailing relatives and two weeks of personal sick leave per year, placing the District at the forefront of jurisdictions with family-friendly workplace laws but alarming employers who say the nation’s capital is becoming an increasingly costly place to do business.

The legislation is the capstone for a council that has pushed unabashedly progressive labor standards. In the past year alone, the city adopted a plan to hike the minimum wage to $15 an hour by 2020, and council members have considered bills that would dictate to private employers how to schedule shift workers and whether they can inquire about salary history when making a job offer.

If enacted, the law would also be the latest in a string of victories that labor advocates have won across the country, most notably on wage standards. Council member Elissa Silverman (I-At Large), who co-wrote the original version of the paid-leave legislation, described the District as a uniquely important role model.

“As we’ve seen with other worker benefit bills, it takes a few leader cities and states to get momentum going, and then we see passage throughout the country,” Silverman said. “I think the District will be seen as a leader, and I think that’s important, because we have a national platform, a national audience.”

Only council member Jack Evans (D-Ward 2) and council member Yvette M. Alexander (D-Ward 7) voted against the bill. Evans cited what he called the “absurdity” of a plan that according to D.C. Chief Financial Officer Jeffrey DeWitt would deliver 64 percent of its benefit payments to Virginia and Maryland residents who commute to jobs in the District.

“This is not like a stadium — I support the stadium or I’m against the stadium. Everybody supports family paid leave,” Evans said. “It’s the mechanism of implementing it we’re trying to get to, and the one you have put forward is totally unacceptable to me, because I cannot sit here . . . and justify paying two-thirds of my money to people who do not live in this city.”

The bill must undergo a final council vote Dec. 20 before moving to Mayor Muriel E. Bowser (D) for a signature or veto. Bowser spokesman Kevin Harris said Tuesday afternoon that the mayor had not yet decided whether to support the legislation. She “remains concerned” about the disproportionate amount of money that would go to commuters, he said.

“The mayor believes in supporting families, but wants to make sure we are putting District families first,” Harris said in a statement.

If the bill becomes law, benefits probably would not be available before 2019, since the city would have to prepare and fund the program. City analysts estimate the cost of a technological system to administer the benefits alone could be as high as $80 million.

The legislation incited fervent support among activists and equally strong resistance among employers, who say they are groaning under the cumulative weight of workplace regulations and taxes the city is heaping on them in its drive to create new social programs and benefits.

“Life has infinite complications, and it’s important that people be able to support their families,” said Amanda Koppelman-Milstein, a 32-year-old Adams Morgan resident who supports the bill and brought her 2-year-old son to the John A. Wilson Building for the council’s vote Tuesday. “You don’t want to be impoverished because your mother has cancer. It’s already bad enough that your mom has cancer.”

But Vincent B. Orange, a former council member who now heads the D.C. Chamber of Commerce, said his members think the benefit is too generous. “D.C. has to take care of D.C.,” he said. “There’s not enough to go around to cover everyone.”

The plan advanced Tuesday was a scaled-back version of legislation proposed more than a year ago by Silverman and council member David Grosso (I-At Large). Their bill would have granted 16 weeks of paid parental leave. Late last month, Council Chairman Phil Mendelson (D) produced a modified bill offering 11 weeks of parental leave and eight weeks of family medical leave but no paid leave for individual workers who suffered sickness or injury.

Some fiscal watchdogs warn that even in its more modest version, the law could be a long-term drag on the city’s budget. Unlike many other times in its history, the District has its finances in order, thanks to relatively conservative fiscal policies and a booming local economy.

But the city is entering a time of greater uncertainty. Its decaying transit system is expected to require heavy investment in the years ahead, and President-elect Donald Trump’s plans for the federal government workforce and federal funding for the District — both crucial to the city’s economic well-being — remain unclear.

Dewitt, the D.C. chief financial officer, has warned the council that although the new tax on businesses would provide enough money to pay employees during their time off, the city has not figured out how to pay for a new bureaucracy to oversee the program.

To pay for the benefits, the city would increase employer-paid payroll taxes by 0.62 percent. Some small-business owners said the new payroll tax could make it more difficult to survive.

Arianne Bennett, who with her husband co-founded the Amsterdam Falafel franchise based in the District, supports the idea of paid family leave but doesn’t think employers should have to bear the full cost. “As a small business, we have teeny tiny razor-thin margins that we live with, and here is another almost 1 percent out the door,” Bennett said.

Employers with existing paid leave policies more generous than the proposed public program would be encouraged to augment it if necessary to maintain their current benefit level.

The United States is one of the few industrialized countries without a national paid leave law. Germany offers a year of paid leave for new mothers and at least 14 weeks for fathers, while France pays for at least 26 weeks of maternity leave and at least 14 weeks of paternity leave, according to the World Policy Analysis Center at the University of California at Los Angeles. Switzerland offers no paid parental leave for fathers but at least 14 weeks for mothers.

In the United States, businesses with 50 or more employees must offer 12 weeks of unpaid leave under federal law. Some states and cities go further: New Jersey and California pay 60 percent of a worker’s salary for up to six weeks, and New York will begin implementing a family leave law in 2018 that will eventually provide workers with 67 percent of their pay for up to 12 weeks.

The bill voted on by the D.C. Council on Tuesday is aimed specifically at low-wage workers. Once fully up and running, it would eventually offer employees 90 percent of their first $900 in weekly salary, and 50 percent of their remaining weekly salary, with payments capped at $1,000 a week. That maximum amount could increase depending on inflation beginning in 2021.

D.C. residents like Ana Chavez say such support would be welcome. Chavez, a 28-year-old single mother, said she took three months of unpaid leave from her job at a Subway sandwich shop when she gave birth to a son last year.

She said she sometimes worked 12 hours a day on her feet until a month before her son was born, stopping only because she was showing signs of pre-term labor and her doctor ordered bed rest. But getting by without a paycheck was a struggle, she said, and she had to strike a deal with her landlord to delay paying rent while she was away from work caring for her baby.

“There was no money,” she said.

Aaron C. Davis contributed to this report.