DETROIT, Aug 14 (Reuters) - The United Auto Workers is

launching a U.S-wide effort to mobilize its one million active

and retired workers to vote for Kamala Harris in the Nov. 5

election, it said on Wednesday, offering the Democrat a

potential boost in critical battleground states.

UAW President Shawn Fain and his executive board endorsed

Harris at the end of July, and Fain has been vocal about his

opposition to Harris' Republican rival, former president Donald

Trump.

The UAW's influence and membership is concentrated in

Michigan, where it is based, along with locations in Wisconsin,

Ohio and Pennsylvania - key swing states that could sway the

outcome of the election.

In 2020, the UAW's membership accounted for 9.2% of U.S.

President Joe Biden's votes in Michigan alone, the union said in

its statement. It said its strategy in this election will

include engaging with members online, at work sites, and

door-to-door outreach.

The UAW declined to outline how much it would spend on its

election efforts, but a person familiar with the program said it

planned to spend millions of dollars.

Fain last week met with Harris and her vice presidential

candidate Tim Walz at two campaign stops around Detroit.

Michigan households with a union member have been more

likely than union households nationwide to vote for a Democrat

in the last three U.S. presidential elections, according to

polling firm Edison Research. In Michigan, those households lean

more toward voting for Democrats than non-union households.

On Tuesday, the UAW filed complaints with the National Labor

Relations Board against Trump and Tesla CEO Elon Musk

citing attempts to threaten and intimidate workers.

During a conversation between the two men on social media

platform X Monday evening, Trump complimented the CEO's ability

to cut costs by saying he would not tolerate workers going on

strike. Musk chuckled but did not respond to Trump's comments.

Harris' entry into the presidential race since Biden stepped

aside last month has energized Democrats and she now holds a

small national lead over Trump, though polls show the election

remains a tight contest.

Trump, who has drawn support in previous election cycles

from some working-class, white voters who would traditionally

have been part of the Democrat base, has earned the backing of

some UAW members who say the former president's record on trade

and tax issues benefits the auto industry more than his

Democratic opponent.

Some unions, such as the International Brotherhood of

Teamsters, have not yet endorsed a candidate. Teamsters

president Sean O'Brien spoke at the Republican National

Convention in July.