(US, politics, transitive, intransitive) To challenge (an incumbent sitting politician) for their political party's nomination to run for re-election, through running a challenger campaign in a primary election, especially one that is more ideologically extreme.

first or earliest in a group or series. / main; principal; chief; placed ahead of others. / (geology) Earliest formed; fundamental.

A primary election; a preliminary election to select a political candidate of a political party. / The first year of grade school. / A base or fundamental component; something that is irreducible.

(US, politics) Mounting a challenge to an incumbent office-holder in a party primary.

present participle of primary

plural of primary

Third-person singular simple present indicative form of primary

simple past tense and past participle of primary

The quality or state of being primary, or first in time, act, or intention.

(psychology) A consequence, such as food or water, that fulfills a primary, unlearned drive, such as hunger or thirst, and thereby reinforces a behavior without dependence on prior learning.