DETROIT, Nov 16 (Reuters) -

General Motors' tentative labor deal with the United Auto Workers (UAW) union has clinched ratification, making its workers the first of those at the Detroit Three automakers to approve the agreement.

Attention now shifts to ongoing voting at Ford and Chrysler parent Stellantis, where the margins in favor of the deal suggest the agreement will be approved comfortably.

The

UAW's GM vote tracking site

shows approval of the contract leading by a 55% to 45% margin with nearly 36,000 workers having cast votes out of about 46,000 UAW-represented GM workers. The votes ratify the UAW's tentative agreement that ended an unprecedented six-week campaign of coordinated strikes.

Voting ends on Thursday at 4 p.m. EST (2100 GMT), although most votes were cast by Wednesday.

While the UAW has not formally announced the ratification, it would mark the first approval of a deal, which runs through April 2028, with one of the Detroit Three. Voting at Ford and Stellantis is still underway.

All three companies agreed to tentative agreements about two weeks ago.

Seven of GM's 11 assembly plants rejected the deal. However, the largest assembly plant in Arlington, Texas, approved the agreement along with assembly plants in Detroit; Fairfax, Kansas; and Lake Orion, Michigan.

The UAW's new agreement with GM grants a 25% increase in base wage through April 2028 and will cumulatively raise the top wage by 33%, compounded with estimated cost-of-living adjustments to over $42 an hour.

Currently, about 67% of Ford workers who have voted are in favor of the UAW deal, and about 66% of Stellantis workers have so far voted in favor, according to UAW figures. Ford voting is scheduled to finish on Friday, while Stellantis is set to close next Tuesday.

Automakers were previously slashing costs and navigating a bumpy road to manufacture EVs and catch up with market leader Tesla, but lower margins on those vehicles have deterred them from accelerating the move.

GM in October also pulled its full-year profit forecast due to the strike and postponed a $4 billion electric truck plant in Michigan.

(Reporting by David Shepardson in Washington and Ben Klayman in Detroit; Editing by Lisa Shumaker)