As the controversial real estate mogul closes in on securing the party's nomination for president his appearances have drawn protests nationwide, including at a rally in Orange County Thursday night.
The stakes are at an all-time high in California as Donald Trump, Texas Senator Ted Cruz and Ohio Governor John Kasich prepare to win much needed support in the Bay Area.
"Depending on what happens in Indiana and the other states that are remaining. This election could be decided in California," says California Republican Party Vice Chairman Harmeet Dhillon.
The California GOP is preparing for one of their highest attended conventions in decades.
The three left standing for the Republican's top spot will address their Californian constituents at the weekend-long event, is being held at the Hyatt Regency in Burlingame, a place that's surrounded by barricades because once Trump announced he was attending, a large number of protesters also said they would show up.
"We're expecting a decent number of individuals; could be 500 could be 3,000. So we've prepared for that," says Burlingame Police Chief Eric Wollman.
Burlingame police said every department in San Mateo County will be offering officers to help with the convention. The sheriff's department already dispatched the command center to be on hand to provide additional resources.
"I went out and requested mutual aid and asked for help. Just to make sure that we have the numbers to maintain the order that we hope to maintain tomorrow," says Wollman.
Trump and Kasich will speak on Friday. Cruz and his running mate Carly Fiorina will speak on Saturday.
The state's GOP says it will also vote on several issues during the convention.
"To extend the term limits for the chairman for either a third term or lifting the term limits altogether. We're also electing the national committee man and national committee woman from California to the RNC," says Dhillon.