Basically: I committed a crime while trying to stay in office illegally, but you can’t hold me to account because I’m running for office.
Pretty much “I’m a big-deal Republican, so you can’t apply the normal rules to me, even though others have run for President from jail”
Fun fact: Precedent exists for presidential immunity. Nixon.
Nixon resigned after Watergate because of the obviously impending impeachment by Congress, and then was subsequently granted a pardon by Ford. It can be legally argued that if presidential (or candidate!) immunity existed in law, in any form, then there would have been no reason to resign or grant a pardon as Nixon could have simply stood beside it and blown raspberries. Therefore, it must not exist in law.
I like that theory, but…
The president does not have the power of judicial review. Therefore President Ford’s actions can’t be construed as such.