Md. Code, Election Law § 5-701
§5–701.
Nominations for public offices that are filled by elections governed by this article shall be made:
(1) by party primary, for candidates of a principal political party;
(2) by petition, for candidates not affiliated with any political party; or
(3) in accordance with the constitution and bylaws of the political party, for candidates of a political party that does not nominate by party primary.