Winslow took 79 votes, compared to 59 for local businessman Gabriel Gomez and 55 for former George W. Bush official Michael Sullivan, according to the Boston Globe.
All three will be on the Republican primary ballot, having turned in the necessary number of signatures last week.
The straw poll was organized by the Massachusetts Republican Party, and cost $10 a ballot. It was held at a Danvers, Mass., yacht club, a location that Winslow criticized.
“They gave us three minutes to speak today; three minutes is longer than I ever wanted to spend in a yacht club,” he said. “I am not a tea and crumpets Republican. I am here because there are activists here. I am running a grassroots campaign.”
Both Winslow and Gomez hired firms to help them collect their signatures, while Sullivan collected his entirely with volunteer help.
Gomez told the Globe that he was surprised at the number of votes he received at the straw poll.
“I’ve got to tell you, I’m thrilled and still in a little bit of shock we got that many votes,” Gomez said.