NASHVILLE, Tenn. — A team of political activists huddled at a Hardee’s one rainy Saturday, wolfing down a breakfast of biscuits and gravy. Then they descended on Antioch, a quiet Nashville suburb, armed with iPads full of voter data and a fiery script.

The group, the local chapter for Americans for Prosperity, which is financed by the oil billionaires Charles G. and David H. Koch to advance conservative causes , fanned out and began strategically knocking on doors. Their targets: voters most likely to oppose a local plan to build light-rail trains, a traffic-easing tunnel and new bus routes.

“Do you agree that raising the sales tax to the highest rate in the nation must be stopped?” Samuel Nienow, one of the organizers, asked a startled man who answered the door at his ranch-style home in March. “Can we count on you to vote ‘no’ on the transit plan?”

In cities and counties across the country — including Little Rock, Ark.; Phoenix, Ariz.; southeast Michigan; central Utah; and here in Tennessee — the Koch brothers are fueling a fight against public transit, an offshoot of their longstanding national crusade for lower taxes and smaller government.