CHATTANOOGA, TN—More than 1,700 workers at Volkswagen’s assembly plant here will go to the polls Wednesday through Friday as the United Auto Workers tries for a breakthrough in its drive to unionize a foreign automaker in the South.

A UAW win among the German carmaker’s production and skilled trades workers wouldn’t just impact the Chattanooga plant, but would be seen by experts as rattling the region.

A flood of print, TV and digital advertising, estimated at well more than $100,000, has hit Chattanooga from not just locals, but groups from places such as Washington, DC, and Michigan.

Workers said they’ve been pressed by pro- and anti-union supporters at the plant and at home.

“Some people have had two or three visits,” says Keri Menendez, a nine-year team leader at the 3,500-worker plant, which makes the Passat sedan and Atlas SUV and has a planned new electric vehicle slated for 2022.

On Tuesday, Hamilton County Mayor Jim Coppinger joined Gov. Bill Lee and some other Republican political leaders in calling for workers to reject the union.

“We have a good thing going here in Hamilton County,” says Coppinger. “Our unemployment rate is below the national average and average weekly wages in our county surpass most all neighboring counties. And Volkswagen is a major reason for our success.”

The election is the third union vote at the Chattanooga factory since 2014. The first ended in a UAW defeat by a margin of 712 to 626. In 2015, the UAW won a vote of a small group of skilled trades workers 108 to 44, but VW never agreed to bargain with them. The UAW this spring later disclaimed that vote for an election of the full production unit this week.

Worker sentiment on the union is split, though employee dissatisfaction in the plant is said to have grown since 2014.