The CNN poll showed that Rubio’s support has plunged to 6% among likely Republican primary voters. In May, he was leading the GOP pack with 14%.
This drop represents the largest shift among any Republican candidate. While most candidates remained statistically within the margin of error, Rubio’s drop is the only significant movement up or down among candidates. He also lost ground in a theoretical head-to-head matchup with Democratic frontrunner Hillary Clinton — he now trails her by 17 points after coming within three in May.