Voting in general elections, If you abstain from voting for either Pres, candidate will all the other choices made elsewhere on the ballot count?

I already know I will absolutely HATE any presidential candidate on the ballot ,and plan on voting for the challengers in the rest of the positions even if they are an unknown, could I just leave the space blank on president or, vote for them both to cancel them out or, write someone in? Our ballots are fill in the oval spot with a #2 pencil next to the candidates name. I don’t want to disqualify the entire ballot if I abstain from the president vote. Anyone ever done this before? Just to be clear I’m neither Republican or Democrat. If a miracle happens and Ron Paul gets the nomination then maybe I will vote, maybe.