From USA Today
Source: Slate.com
"The survey by Washington-based Mercury Analytics is a combination online questionnaire and "dial-test" of Trump's first big campaign ad among 916 self-proclaimed "likely voters" (this video shows the ad and the dial test results). It took place primarily Wednesday and Thursday and has a margin of error of plus or minus 3.5 percent.
Nearly 20 percent of likely Democratic voters say they'd cross sides and vote for Trump, while a small number, or 14 percent, of Republicans claim they'd vote for Clinton. When those groups were further broken down, a far higher percentage of the crossover Democrats contend they are "100 percent sure" of switching than the Republicans."