An alternative to the teachers union's business tax may be on the 2014 ballot with the governor's backing, Senate Minority Leader Michael Roberson, R-Las Vegas, said Wednesday.He and several other Republican senators rolled out the plan Tuesday saying they will support passage of the amendment taking the special limit on mining taxes out of the Nevada Constitution.They said if mining pays some more, the “ruinous” business tax proposed by teachers can be avoided.They also said they will develop an alternative to that ballot question imposing a margins tax on businesses in the state.The teachers' initiative petition will go directly to …