D.C. Council member Jack Evans (D-Ward 2), shown, and Mary Cheh (D-Ward 3) are proposing substantial changes to the city’s paid leave bill. (Katherine Frey/The Washington Post)

Two D.C. Council members are proposing dramatic revisions to the city’s landmark bill guaranteeing up to two months of paid time off for new parents, setting up a showdown among rival council factions and Mayor Muriel E. Bowser as the council meets Tuesday to take a final vote on the legislation.

The alternative bill from members Jack Evans (D-Ward 2) and Mary M. Cheh (D-Ward 3) would guarantee the same amount of paid leave as the existing bill, to which the council gave preliminary approval earlier this month: eight weeks for new parents, six weeks to care for an ailing family member and two weeks of personal sick time. It would be among the most generous paid family leave laws in the country.

But rather than taxing businesses to fund those benefits, Evans and Cheh want to require that private employers provide the specified amounts of time off. Businesses with 70 or fewer workers would be eligible for a $200-per-employee annual tax credit to ease the cost of compliance.

The last-minute maneuvering came as the impact of paid family leave on businesses large and small dominated the public debate about the bill.

More than a year in the making, the existing version of the legislation would be a coup for the council’s progressive lawmakers and a setback for Bowser (D), who has repeatedly fought it, citing its expense and the fact that most District workers who would benefit live in Virginia and Maryland.

The changes — announced unexpectedly Monday when Evans and Cheh showed up at a news conference held by Council Chairman Phil Mendelson (D), who drafted the current paid-leave bill — are backed by major business interests in the city.

In a full-page ad in Tuesday’s Washington Post, the business community wrote an open letter to the D.C. Council, calling the Evans and Cheh legislation a “better, faster and cheaper” way to provide family leave and promising to seek a mayoral veto if the council passes the current version. It was signed by the Greater Washington Board of Trade, the D.C. Chamber of Commerce, the Federal City Council and associations representing restaurants, hotels, parking garages, universities and hospitals, among others.

Evans said the mayor was also backing his legislation.

In an interview Monday evening, Bowser said the revised bill proposed by Evans and Cheh is “more likely to win my support.” If it advances in the council, she said, “I’m pretty sure I’d be very comfortable with it.”

“I can say this: If I was on the council, I’d be voting for it,” she said.

The mayor said she would not sign the current version of the paid-leave bill passed by the council. However, she declined to say whether she would veto that legislation — a critical decision, because a bill can become law without the mayor’s signature if she does not veto it.

Some businesses that already guarantee paid time off oppose Mendelson’s legislation, which would increase employer-paid payroll taxes by 0.62 percent to fund the same benefits for workers whose employers don’t provide them.

Robert Kinsler, owner of a company that organizes social sports leagues for adults and special events, said he preferred the employer mandate to the previous paid-leave bill, which he said would likely require his company to pay more in taxes than it would receive in benefits. He said he was also reluctant to allow the city to act as a kind of human resources department, effectively vetting and managing time off for his eight full-time workers.

“The idea of outsourcing employee benefits gives me chills and nightmares,” Kinsler said.

Roger Horowitz, owner of the Pleasant Pops coffee shops in Adams Morgan and downtown, supports the existing bill. The proposed tax increase under that plan would amount to about $2,000 a year for his 22 employees, which is “not a very significant amount of our revenue,” Horowitz said.

But it would allow him to offer paid-leave benefits he can’t currently afford, reducing turnover and leveling the playing field with bigger businesses when it comes to attracting workers, he said.

“We would love to offer paid leave, and we always felt we were at a disadvantage as a small business being able to do that,” he said.

Evans and Cheh say their revised bill would cost the city an estimated $40 million a year, compared to $250 million for the current legislation. They said their proposal is a streamlined approach to reaching the goal of paid leave for all private-sector workers in the District.

Cheh voted for the current bill two weeks ago; Evans did not.

Critics call their plan a sop to the city’s large employers. Mendelson said the $200 tax credits would do little to cushion the blow of a paid-leave mandate for small employers. The cost of two months’ parental leave for a single, minimum-wage employee exceeds $4,000.

“It’s not hard to understand,” Mendelson said. “It doesn’t work.”

And without a new tax, it was not clear how the District would generate $40 million annually for paid-leave subsidies to small businesses, he said.

Evans acknowledged that big employers supported the new version of the bill because it would have little effect on them. “Large businesses like this, because they’re doing it already,” he said.

He said it would also help small-business owners, however, by not burdening them with another tax. Employers who have trouble paying for the mandated time off could also apply to the city for extra funds, he said, although the process for doing so is not clear.

Council members gave preliminary approval to the leave bill in its current version on Dec. 6 with only Evans and Yvette M. Alexander (D-Ward 7) casting dissenting votes. Seven of the council’s 13 members will have to vote for the bill again if it is to become law.

Mendelson said he is confident the current version of the bill has enough support to pass. “I haven’t done a count,” he said. “But my guess is I have more than seven votes.”

Fenit Nirappil contributed to this report.