This fact checker report in the Washington Post raises several questions about Romney's job creating plan. Perhaps the easiest question comes from economic forecasting groups. They forecast similar growth over that period no matter who is elected as president. The rest of the article raises questions about the studies that Romney's campaign cites to support its claims.
The problem with US election campaigns is that Romney's claims are advertised heavily. Few will be aware of the problems with his claims. Lying is the best way to run an election in the US.