The world belongs to those who show up
I am a delegate to both the North Carolina state GOP convention to be held in May and my congressional district convention next week. My political insider connection is that I showed up at my precinct caucus/county convention last month, where I expressed the willingness to commit to the time and expense of attending these other conventions.
I have made a similar commitment every few years for the past three decades. When I lived in Chicago, I was also a delegate to several Illinois state GOP conventions for the same reasons: I voted in Republican primaries, attended my ward Republican organization's meetings, and made the commitment to attend the state convention. As a law professor I had who was also a veteran of the Minnesota state legislature used to tell his class, “The world belongs to those who show up to participate.”
The sad fact is that many times, delegate/alternate slots to political conventions go unfilled because there are not enough people willing to participate. A county convention may take from half to a full day, depending on the size of the county. A congressional district may also may take up to a day. The state party convention's general assembly is also an entire day, and unless the state convention is in one's hometown, attendance involves at least one night's stay in a hotel. Plus there are registration fees to pay and travel costs.
There is one big difference this year. As I listen to Trump whine about how unfair it is that he actually has to come up with hundreds of warm bodies willing to spend the time and money to go to Cleveland to cast the votes he won through his plurality finishes in various primaries, I marvel at the incredible level of organization inside Ted Cruz's campaign. I have been told that before I moved here in 2003, no one ever showed up at the Republican Party caucus for the precinct where I now live. It is heavily Democrat, and it is also the longest drive of all the various precincts to the county seat where the caucus/county convention is held. Since I moved here, it had always been a caucus of one. This year, however, there were three. Ted Cruz's campaign found two people in this tiny precinct in this rural backwater of a county who were heretofore not involved in local politics and who are willing to commit to attending the county, congressional district, and state political conventions to support Ted Cruz.
If there were any Trump supporters at the Republican convention in my county, they uncharacteristically kept silent.