From Bloomberg Politics:
Wisconsin Governor Scott Walker has expanded his early lead in Iowa, while former Florida Governor Jeb Bush continues to face headwinds and Senator Marco Rubio of Florida shows upside potential in the state that hosts the first 2016 presidential nomination balloting.
A new Bloomberg Politics/Des Moines Register Iowa Poll shows more than a third of likely Republican caucus participants say they would never vote for Bush—one factor in a new index to assess candidate strength in such a crowded field. Forty-three percent view him favorably, compared to 45 percent who view him unfavorably.
Walker is backed by 17 percent as the state enters a busy summer of candidate visits, a planned straw poll, and campaigning at the Iowa State Fair. Tied for second are Senator Rand Paul of Kentucky and retired neurosurgeon Ben Carson at 10 percent, with Bush and former Arkansas Governor Mike Huckabee next at 9 percent each.