The 2016 Republican presidential field could be bigger than any in recent memory – thanks to a growing second tier of potential contenders.

While several prominent politicians already have insinuated themselves into the mix, from Ted Cruz to Rand Paul to Chris Christie to Jeb Bush, a number of under-the-radar names are now flirting with a 2016 candidacy. 

They may be the long shots, but could shake things up -- by playing the spoiler in key primaries, positioning themselves as a potential running mate for the eventual nominee or even becoming a dark horse competitor in the final stage. 

"It is definitely a new phenomenon," Ronald Reagan biographer Craig Shirley said of the increasingly crowded fields. (The 2008 and 2012 GOP contests were a political demolition derby.) "I don't think this has anything to do with the growth of the United States, you just have more people who are convinced they are qualified to run for president." 

Some potential candidates are hardly new to the game, including Rick Santorum and others. 

Longtime Republican pollster Glen Bolger said the lure is especially strong for pols who have inhabited that spotlight. "They figure, Barack Obama can come out of nowhere," he said, referring to the president's leap from one-term senator to president. "They think, 'I can be different, I can break the mold and get the nomination'." 

He added: "[But] it's like catching lightning in a bottle. I won't say it can't be done, but that's what a lot of these candidates are relying on." 

Here's a look at a few of them: