Truth be known, very little of the voting population is "up for grabs". Union member votes in federal elections comprise 25% even though unions are about 13% of the total U.S. work force. Add to this 92% of black voters, 85% of Jewish, and the vast majority of new immigrants and the Democrats have about 42% before the nomination process even begins. It does not matter who is nominated. Clinton got 42 1/2 % of the total vote count when he was first elected in 1992. The great "middle", mostly rural America and Christians, give the Republicans about 48%. That means 90% is not open for change unless it involves misconduct. The 10% remaining is actually +/- 5% if you want to look at it that way.