a closed political meeting
"The party leaders held a private caucus to decide on their candidate before announcing it to the public."
A usually preliminary meeting of party members to nominate candidates for public office or delegates to be sent a nominating convention, or to confer regarding policy.
"The local Democrats gathered in the town hall to hold their caucus and select who would represent them at the state convention."
meet to select a candidate or promote a policy
"After months of debate, the local party members finally gathered for a caucus to officially select their nominee for mayor."
To meet and participate in caucus.
"The party members gathered for a private caucus to decide their candidate before the primary election."