The caucus selects who gets 18 of the delegates the state's 20 delegates. The other two delegates are the GOP chairman and chairwoman, who will be unbound delegates, and they are selected at the Hawaii state convention.
During the 2008 presidential campaign, Hawaii's GOP delegates were selected at the state's Republican convention. GOP presidential candidate Sen. John McCain of Arizona ultimately got all 20.
Only registered GOP voters can participate but residents can register to vote at the caucus sites.
The state GOP decided to conduct caucuses as a party-building tool after record turnout for the 2008 Democratic caucuses, when Hawaii-born Barack Obama was running for president, the Hawaii Free Press reported.
The campaign for U.S. Rep. Ron Paul of Texas, who consistently is last among the four major candidates -- Mitt Romney, Rick Santorum and Newt Gingrich are the other three -- hosted an event in advance of the Aloha State's inaugural primary, The Washington Times reported.
"On March 13, voters in Hawaii will head to their local caucus to choose which Republican they want to see take on Barack Obama in November," Paul told supporters in an e-mail. "And with so much at stake this Election Year, this decision is not something voters should take lightly."
The Times reported Paul has raised more campaign contributions from Hawaii residents than any of his Republican rivals.