The bottom has fallen out for Jeb Bush. The newest poll of Iowa has Bush at 5 percent. He’s at 7 percent in New Hampshire and 9 percent in South Carolina. As recently as mid-July, Bush sat atop the Real Clear Politics national average, eight points ahead of his nearest competitor at 17.8 percent. Now, he trails Donald Trump and Ben Carson, in third at 9.7 percent.

Bush’s well-documented weaknesses as a candidate — perceived conservative heresies on immigration and Common Core, a politically inconvenient last name – didn’t seem to be hurting him when he was on top seven weeks ago. So what explains his sudden slide?

Alex Castellanos, a former ad-man for George W. Bush’s reelection campaign and a CNN commentator, suggests that frontrunner Donald Trump is making Bush look small.

“Americans are afraid their nation is in decline; they are going to lose the country they love,” Castellanos says. “They want a leader as big as their fears. Right now, a lot of Republicans see that big leader as Trump, and no else is at the big boys’ table with him.”