Ron Paul is orchestrating a highly unusual, yet precisely organized, grassroots effort to bring as many loyal delegates as possible to the Republican National Convention. Romney's campaign has some mass appeal but invites little passion. Paul's might have even fewer supporters than Romney but their energetic zeal could culminate in having an outsize influence at the RNC without having won a single primary.
Each state selects its delegates to the Republican National Convention differently, and as has often been reported, the process of a candidate “winning a state” is not as simple as a plurality on primary day. An obscure process of country, district, and state conventions exists to appoint these delegates to the national convention. A candidate who can successfully manipulate these lesser known “behind-the-scenes” processes can put himself in an advantageous position should the Convention begin in August with some doubt about the identity of the nominee.
Be sure to read the rest at the link. I'm not sure I would call it "hijacking", though. I prefer to think of it as being well-organized and strategic.