Rubbish.
In 2012, whites were 74% of the voters, blacks 13%, hispanics 8% and asians 3%. If every black, every hispanic, and every asian voted communist, that would be 24% of the total vote.
Willard M. Romney won 59% of the white vote.
If the GOP would concentrate on increasing it's share of the white vote (every percent increase cancels 3% of the minority vote) they would never lose another election.
White women are not voting for republicans. When you lose white women you lose the race.