Let's be precise here. Voting is generally IMO a bad idea but does not always = Violence.

Violence through proxy i.e paying or supporting someone initiating a violent action is immoral.
The assumption that expressing a preference for an individual to run for president is always tantamount to a moral infraction is however a generalization. If the said individual is running to expand or enable the government system, then the argument would be valid.
That being said, one can support a candidate like Adam Kokesh or Ron Paul that has/is runing to abolish government or
implement the succession of states from government.
Asking a murder to kill an individual is wrong, asking a murderer to avoid killing individuals is NOT a violation.

Therefore supporting a candidate running under the basis of eliminating government is not a violation of The NAP.

The error people make is that they are appealing to the potential for candidates running to expand the government or perform other violations of individual freedoms. That is however not always the case and is an appeal to potentiality fallacy.