None of them had a niche.
Graham - How many Republican primary voters do you think base their vote on being a hawk, and of those, how many do you think would be okay with "Grahamnesty?"
Huckabee - Old news, his pandering style was very dated
Santorum - Old news, only got traction in 2012 because he was at the right place at the right time to be flavor of the month against Romney, someone who many Republican primary voters disliked
Perry - Old news, literally a joke candidate best known for forgetting which agency of government he'd abolish
Jindal - Brought nothing to the table, and his name is literally "Piyush Jindal." Need I say more?
The first part was good, LOL.
Seriously, though, you win a nomination by uniting factions. Though it's hard to remember in the hyper-polarized age of Trump, the GOP still has factions, just like the Democratic Party. Of those, Jindal, Huckabee and Santorum solely appealed to the Religious Right. They had almost no appeal to the far right crowd, moderates, donors, etc. Graham only appealed to the foreign policy hawk crowd, which is much bigger among elected officials and donors (and donors usually bet on who they think could actually win, among equally preferable candidates). Perry could have gone somewhere, but he had the gaffe. After that, why not just find another, better Perry?
McCain, Romney and Trump all united different GOP factions that probably would not have preferred "that type of candidate" on paper but came to be won over through the primary process. Despite how we talk, the 2008 Republican primary electorate that elected John McCain is hardly any different from the one that elected Romney, which is hardly any different than the one who elected Trump.
