CHATTANOOGA, Tennessee, April 20 (Reuters) - The United

Auto Workers has made history by winning its first unionization

vote at an auto factory in the U.S. South. Now it needs to prove

the success wasn't a fluke by pulling off a second victory at a

Mercedes plant in Alabama next month.

UAW representatives at the VW plant also will have to show

their mettle by negotiating a contract that gives workers what

they have fought for - better benefits, improved safety on the

job and a greater work-life balance.

The Volkswagen landslide win in Tennessee is

expected to provide crucial momentum to UAW President Shawn

Fain's $40 million campaign to expand the union outside Detroit

to the U.S. South and West, focusing on 13 non-union auto

companies, including Toyota ( TM ) and Tesla.

Fain, a scrappy leader who reveled in last year's fight

with Detroit companies that won double-digit raises and

cost-of-living adjustments, told a party of VW workers that the

union would carry the fight on to Mercedes. "Let's win more for

the working class all over this nation," he said.

The Mercedes plant vote, scheduled for mid-May, is expected

to be a tougher fight than at VW, which took a neutral position

in the vote.

Mercedes has said it respects workers' right to organize and

wants them to make an informed decision. But in a letter to

employees in January, it said that the union organizers "cannot

guarantee you anything" and that some workers had said no to

unionization because of Mercedes' competitive pay and benefits.

"Mercedes is running a much more aggressive anti-union

campaign than Volkswagen within the plant," said John Logan,

labor professor at San Francisco State University.

But he added that the large VW victory that saw 73% of

eligible workers vote in favor will provide significant momentum

for organizing efforts at other plants in the South.

"This will give them a huge boost for the Mercedes vote, and

if they win that one, too, I wouldn't be surprised to see

elections at Hyundai, Honda and Toyota ( TM ) over the next several

months," he said.

The UAW says a "supermajority" of the roughly 5,200 eligible

workers at the Mercedes assembly plant in Vance, Alabama, and a

nearby battery plant in Woodstock support it. UAW policy is to

push for a vote once 70% of workers have signed union cards.

Much may depend on economics and perceptions about job

security. In the traditionally anti-union South where the UAW

has lost several fights in the past, six Republican governors

have flatly opposed the union's current campaign, describing it

as risking job security since automakers face higher labor

costs.

Prior to last autumn's UAW labor talks with the Detroit

Three automakers, Ford officials said their U.S. labor

costs were $64 an hour, compared with an estimated $55 for

foreign automakers and $45-$50 for electric vehicle leader

Tesla.

Workers at two other plants in the U.S. South - a Hyundai

plant in Alabama and a Toyota ( TM ) parts factory in

Missouri - have also launched organizing campaigns, with 30% of

employees signing cards saying they support the UAW.

Workers at the VW plant say they will kick off meetings on

Sunday to strategize on contract negotiations.

"The real fight is getting your fair share," Fain told VW

workers Friday night.

VW worker Jeremy Bowman, who hopes to be on the plant's

organizing committee, agreed. "The fight is just starting," he

said.