With less than two weeks before Arizona's 2018 primary, one candidate appears to be pulling away from the field for the GOP Senate nomination, according to a new poll.

The latest numbers from an OH Predictive Insights/ABC15 poll have likely GOP primary voters overwhelmingly in support of Arizona Rep. Martha McSally as the pick to challenge to replace retiring Sen. Jeff Flake.

In a survey of 578 Republican and independent voters, 47 percent said they would most likely vote for the congresswoman from Arizona's second district. Twenty-seven percent picked former state legislator Dr. Kelli Ward and 13 percent were in favor of former Maricopa County Sheriff Joe Arpaio. Twelve percent said they were unsure or had yet to decide.

McSally's support has increased by double digits since a similar poll conducted at the beginning of the month found she had 35 percent support. Ward's share remained unchanged between the two polls and Arpaio's decreased by about two percent.

The poll was conducted on August 14th and 15th through landline phone interviews. The margin of error is four percent.