Look at the difference in campaign contributions between Tester and his challengers. Which PAC's donated to his campaign, who is behind the PAC's? Between voter fraud, shady PAC's and DNC/corporate donors, his challengers did not stand a chance of winning. Follow the money.
True, it's a damn shame we are not aware of certain FEC info before elections are held. An EO directing that all campaign contributions must be posted before an election would be helpful, we should know in advance who is behind the candidates. Also, get rid of PAC's, they are nothing more than shell games for bad actors. We need more transparency before elections are held.