The headline sounds like a Trump-ism and it probably resembles what Trump will say when he announces his run as an independent around July 2016. Here’s the thing, without a binding agreement, the pledge is nothing more than a great way for the GOP to earn media and for GOP chair Reince Priebus to look like he’s leading the party, but he’s missing a crucial element: Trump’s supporters aren’t necessarily ardent Republicans, they are just conservatives.
Confusing partisanship and ideology is fairly commonplace in American politics and it remains confusing for some studying political behavior at the graduate level. Yes, partisanship and ideology are closely related, with most liberals identifying as Democrats and most conservatives identifying as Republicans, but one’s ideology doesn’t mean they are “party people.” Yes, they may tell a pollster they are a “Republican,” but that may have more to do with their ideology lining up with one particular party than the strength of their partisanship. (Essentially, the Republicans better represent a conservative ideology, therefore a conservative identifies as a Republican.) Trump attract ideologues on the right. Conservatives who fully agree that we need to kick out the “illegals” and build a gigantic wall along both the Mexican AND Canadian borders don’t necessarily rock elephant lapel pins and pendants, but they do support the tea party and other movements associated with the Republican party, but more explicitly tied to the conservative ideology.
This is an important point for Priebus and other Republican bigwigs worried about the Trump-effect. Trump can sign the loyalty pledge now, in early-September 2015 when the stakes are high for both Trump and the Republican Party, but if Trump’s support among Republican party elites starts to wane, but his support among those identifying as very conservative remains high, the likelihood Trump bucks the pledge and runs as an independent strengthens.