Why is Obama claiming victory wherein he did not even met the necessary delegate votes?

Obama is claiming victory and telling her to drop out because he knows that she is still VERY capable of beating him. Truth is, Obama can't beat McCain without Clinton as his VP. Funny thing is, Hillary would never be his running mate. Therefore, the DNC will choose Hillary Clinton as the democratic nominee. Obama is afraid and he knows that he doesn't stand a good chance against McCain.