Pro-Lankford group's poll: Lankford 48%, Shannon 26%

From the Foundation for Economic Prosperity; the main pro-Lankford super PAC:

The following outlines the key findings from a survey of n=500 likely Oklahoma GOP primary voters commissioned by the Foundation for Economic Prosperity, Inc.  Interviews were conducted May 27-29, 2014, with 20% of interviews being conducted with a cell phone sample of those who could not be reached on a landline.  The margin of error for the entire sample is +/- 4.4% at the 95% confidence level.  The margin of error among sub-groups is greater.

James Lankford’s vote share has grown dramatically over the past month.
  Lankford now leads Shannon 48%-26%, with Brogdon at 4%, 3% voting for other candidates and 18% still undecided.  In our last survey (April 27-29), Lankford only led by 2-points (36%-34%).
 Lankford’s favorable to unfavorable ratio has grown from 60:8 last month to 67:6 today.  During that same period, Shannon’s F:U has essentially been unchanged (66:6 in April, 64:9 today).
 More importantly, among those who have a favorable opinion of both candidates (51% of the electorate), Lankford leads Shannon 61%-26%. Lankford’s lead is driven by the fact that he is being seen as the strongest conservative in this race and the one best equipped to take on President Obama.
 Lankford tops 50% with very conservative voters (51%-27%), with only 15% still undecided.
 By a margin of 54%-19%, voters agree that “James Lankford is the candidate best suited to stand up to President Obama and overturn his failed policies.”

James Lankford is in the driver’s seat at this stage of the campaign and it’s clear that T.W. Shannon’s allies have gone negative in an attempt to save him from not making a runoff with Lankford