Democratic Senate candidate Sarah Riggs Amico on Wednesday nabbed the first union endorsement in the race to challenge U.S. Sen. David Perdue, a sign her efforts to woo labor groups have gained early traction.

The endorsement came from Local 613 of the International Brotherhood of Electrical Workers, an Atlanta-based union that represents more than 5,500 workers. The group has also contributed $5,000 to her campaign for Senate.

Amico has made courting labor a key part of her campaign strategy, and joined striking AT&T workers on a picket line hours after she entered the Senate race, telling them she fought to preserve jobs for her car-hauling firm's union members even as it filed for bankruptcy.

The union's endorsement could touch off a bigger scramble to lock of labor support. Despite the declining clout and membership of labor unions, they remain central to Democratic politics in Georgia.

Amico also said she amassed about $710,000 since she entered the race in late August. Her campaign would not say how much of that sum was raised by donors and how much came from loans or other forms of contributions.

Kenny Mullins, the business manager for the union, called Amico the “only candidate in this race who has consistently chosen to hire union labor when she had the choice” and credited her for saving and creating thousands of union jobs.

Amico joined the race for Senate less than a year after she lost the race for Georgia lieutenant governor, and weeks after the car-hauling business she led filed for bankruptcy protection.

She has cast her company’s financial struggles as a key factor in her decision to challenge Perdue, a first-term incumbent and ally of President Donald Trump who she said failed to help struggling pension funds that her firm and others relied upon.

Amico is one of four candidates in the race to challenge Perdue, and the others have also sought to appeal to labor unions.

Clarkston Mayor Ted Terry has pointedly noted on Twitter he's the only contender who is a union member. And the two other candidates – former 6th District candidate Jon Ossoff and former Columbus Mayor Teresa Tomlinson – have courted union backers.

The Perdue contest is one half of a Senate doubleheader in Georgia that has trained the nation’s attention on the state. Gov. Brian Kemp will soon appoint a replacement for retiring U.S. Sen. Johnny Isakson who would also be on the 2020 ballot.