The D.C. Council on Wednesday is scheduled to take a first vote on a closely watched bill that would require large businesses to pay their employees a “living wage” of $12.50 an hour — a significant increase over the current D.C. minimum wage of $8.25.

With roughly 24 hours till the vote, the fate of the Large Retailer Accountability Act remains very much uncertain. John A. Wilson Building vote counters say sentiment on the bill is closely split, with at least four still undecided as worker advocates and business lobbyists pound the hallway carpet trying to lock up support for their respective positions for and against the bill.

At least one amendment is expected to be offered at Wednesday’s meeting. David A. Catania (I-At Large) will propose to restore language, stripped out in committee, that restricted the bill’s impact to retailers operating in spaces of at least 75,000 square feet. Without that proviso, the bill applies to all retailers associated with a company that does $1 billion or more in yearly sales, with an exception for businesses that have entered into collective bargaining agreements with their employees.

The square footage requirement would ensure the law applies more squarely to “big box” retailers like Wal-Mart — whose pending entry into the city prompted the bill — rather than a broader assortment of big-name businesses like Apple, Nike and others that operate out of smaller spaces. The expansion of the bill’s effect amplified opposition from business groups, including the D.C. Chamber of Commerce and the Greater Washington Board of Trade.

The square-footage amendment has won the support of a key party — Chairman Phil Mendelson (D), who introduced the bill in January with square-footage language included. (The Committee on Business, Consumer and Regulatory Affairs, led by Vincent B. Orange (D-At Large), removed it last month.)

But while Catania has conditioned his support for the living-wage bill on passage of the amendment, Mendelson said Tuesday that he will vote for the bill whether the amendment succeeds or not.

Mendelson added that he was confident of its ultimate success regardless of whether the amendment succeeds. “I think the the votes are there,” he said.