Fain said Wednesday the union continues to seek double-digit wage increases. The UAW most recently sought 36% hikes – down from initial demands of 40%. The union's raise proposals to the automakers have not fallen below 30%, he said.

Key demands from the union have included 40% hourly pay increases, a reduced 32-hour work week, a shift back to traditional pensions, the elimination of compensation tiers and a restoration of cost-of-living adjustments, among other items on the table.

Ford CEO Jim Farley said late Tuesday night the company remains "optimistic that we can reach an agreement with the UAW in the next two days."

However, he said there are limits to what Ford is willing to offer.

Farley said the company's latest offer includes "pay increases, elimination of tiers, inflation protection, five weeks of vacation, 17 paid holidays [and] bigger contributions for retirement."

"We put an offer in today that's our most generous offer in 80 years of the UAW and Ford," Farley said during the in Detroit. "It's a significant enhancement, still optimistic that we'll get a deal. But there is a limit because we have to protect for the future, future investments and the profitability of the company funds those."

Farley said Ford is "not going to support" a four-day workweek.