Via Roll Call, the Cruz campaign has released the results of an internal poll which shows Cruz in the lead:

Ted Cruz led Lt. Gov. David Dewhurst by 9 points in a recent internal poll conducted for the former Texas solicitor general’s campaign, a Cruz source has confirmed.

From the earliest days of the race to replace retiring Sen. Kay Bailey Hutchison (R), Dewhurst has been the frontrunner. But in this survey, 49 percent of respondents said they would vote for Cruz. Forty percent supported Dewhurst, and 11 percent were undecided.

The poll surveyed 750 likely Republican runoff voters June 24-26 with a 3.6-point margin of error. Cruz had 96 percent name identification among those voters and Dewhurst had 98 percent name identification.

I haven’t been able to find any other recent polling.  Is this an outlier, or is the Cruz surge the real deal?