Rubio’s 15 percentage-point drop coincides with the rise of Gov. Scott Walker, who’s now in third place with 13 percent – an 11 point increase for the Wisconsin governor since the April survey.

“And the center of the GOP political universe of late — Donald Trump — is in fourth with 11 percent,” Mason Dixon pollster Brad Coker said in a written analysis.

“This is the first Florida poll taken entirely since Trump’s remarks regarding John McCain’s Vietnam War service. His 11% showing in Florida is far below his support in recent national polls. This could be the result of the home state advantage of both Bush and Rubio,” Coker wrote. “However, the fact that Walker has slipped ahead of him may be a stronger sign that his candidacy is fading. Furthermore, there is a clear ceiling that Trump has among Florida Republicans. When asked if they are considering a vote for Trump, a large majority (58%) said they were not. Only 27% gave an indication that Trump was under their serious consideration.”