As Volkswagen workers vote, Tennessee senator ramps up anti-union talk

* Corker: if UAW voted down, VW will announce investment

* VW denies vote, future investment are connected

* Outcome of three-day secret ballot remains too close to call

* A win at Tennessee plant could galvanize weakened UAW

By Richard Cowan and Bernie Woodall

WASHINGTON/CHATTANOOGA, Tenn., Feb 13 (Reuters) - One of Tennessee's two U.S. senators ramped up his anti-union rhetoric on Thursday in an attempt to sway workers at Volkswagen AG's Chattanooga plant who are voting this week on representation by the United Auto Workers.

Republican Senator Bob Corker told Reuters on Thursday that he is "very certain that if the UAW is voted down," the automaker will announce new investment in the plant "in the next couple weeks."

Corker's latest remarks seemed to contradict an earlier statement by Frank Fischer, chief executive of VW Chattanooga, that there was "no connection" between the vote at its three-year-old Tennessee plant and a looming decision on whether VW will build a new crossover vehicle there or in Mexico.

Volkswagen headquarters in Germany declined further comment and referred to Fischer's statement.

Pro-UAW workers and UAW officials have said the plant will get the new product regardless of the final vote tally, because making only one vehicle is not cost-efficient for VW at a plant designed to build at least two vehicles.

The clashing statements injected further uncertainty into the outcome of the three-day election, whose implications extend far beyond Chattanooga. If the vote, which ends on Friday evening, favors the UAW, it would galvanize a union that has lost 75 percent of its members since 1979.

Both union and anti-union forces spent much of the week promoting their views through newspaper ads, websites and billboards.

The Center for Worker Freedom, a special project of Americans for Tax Reform headed by conservative Grover Norquist, purchased 13 billboards in the Chattanooga area, including 11 digital boards.

One billboard links the UAW to President Barack Obama, whose national approval ratings are low, and another links the union to the demise of Detroit, which filed the biggest municipal bankruptcy in U.S. history last July.

The anti-union Southern Momentum group paid for the production of three videos available on its website www.no2uaw.com, including one of a former Volkswagen worker at the company's shuttered plant in Pennsylvania that once made the Rabbit, and another one narrated by an actor that lays out a litany of UAW offenses, including support for liberal political groups that fight gun control.