And by planting what looks like a bold idea--that the purpose of campaigning is to engender optimism and renew our faith--he erases his obligation to tell us how he would govern.
His is a very effective campaign strategy. 
mnli hypothesis: His is a very effective campaign strategy.  premise: And by planting what looks like a bold idea--that the purpose of campaigning is to engender optimism and renew our faith--he erases his obligation to tell us how he would govern.