absolutely.
he is from a supposed 'swing state'
he is a far right fundie, which (in theory) would help mitt with the white, southern fundie crowd.
McDonnell is neither southern nor a fundie (fundie Protestant at least). He was born in Philadelphia, lives in the DC suburbs and is Catholic. He could still perhaps excite southern fundies but isn't really either himself.
where he was born is irrelevant.
and catholics can be fundies too...just look at rick santorum. and as the primaries have shown us, white southerners trust the catholic fundie over the mormon.