Never mind their candidates will not get a single vote; but they will win because voters would have rejected BJP and Congress by giving them negative marks..
That's what the upshot of your comment is.... signifying as if there is never a POSITIVE vote that someone casts in anyone's favour, but is rather a penalty that the voter takes "away" from the party he doesn't like... Fair enough... My question to you - If voter rejected the Congress, why didn't Indian Union Muslim League not get into power in Karnataka?..
Answer is - they didn't contest elections.... Which shows that in order to come to power, you HAVE to compete, you HAVE to grab the vote share, you HAVE to win, and you HAVE to form a government,.. . .
It doesn't just HAPPEN because the voter chose to throw out X party