Billionaire and climate change activist Tom Steyer is considering a run for the U.S. Senate in 2016, vowing to serve only one term if he fails to meet goals involving the environment, economy and education, he told the Sacramento Bee on Sunday. The 57-year-old Democrat's pledge would be part of his formal campaign launch if he decides to run to replace California Sen. Barbara Boxerin. Steyer has outlined three policy goals in lowering emissions, overhauling the federal tax system to see the highest earners paying taxes that reflect their wealth and expanding public education through college. If Steyer were unable to meet his goals, he would resign after his six-year term, he told supporters. A decision could come as early as next week.