There can be but it is no guarantee. There are a lot of former Democrats in the Green Party and the Progressive Party.
Given his earlier position, he would be uniquely qualified to call BS on Hillary's claims concerning her handling of sensitive materials. Provided he doesn't have a skeleton of a similar nature in his closet. Hopefully, that is being carefully vetted.
Let’s remember that that paragon of virtue and integrity James Comey WAS a registered Republican.