Rep. James Lankford led national Tea Party favorite T.W. Shannon in a survey of Oklahoma GOP primary voters commissioned for an organization supporting the congressman.

The Tarrance Group poll, conducted May 12-14 for Families for James Lankford, showed Lankford with 43 percent and Shannon at 33 percent with 18 percent undecided. The margin of error was plus or minus 4.5 percent.

Lankford, who serves in House Republican leadership as the Policy Committee chairman, is battling Shannon, a state legislator who recently stepped down as state speaker, for the seat being vacated by Sen. Tom Coburn, R-Okla.

In the survey memorandum obtained by the Washington Examiner, GOP pollsters Ed Goeas and B.J. Martino wrote that Lankford begins this contest with significant advantages.

"… among those Republican voters who have voted in at least three of the last four Republican primaries, Lankford leads by fully 24-points," they wrote. "Furthermore, Lankford holds an intensity advantage over Shannon, which reveals itself not only in the ballot, but in Republican voters’ perceptions of each of them.”

Lankford is viewed as holding the advantage at the outset of this primary because of statewide name identification he has accrued among conservatives during his days as an activist before being elected to Congress. But the national Tea Party establishment has gravitated toward Shannon, who is African-American, perhaps because they view Lankford as part of the GOP’s D.C. establishment.

However, Oklahoma Tea Party groups do not necessarily share that view. In April, a collection of Sooner State Tea Party activists released an open letter questioning Shannon's conservative credentials and criticizing nationally well-known conservatives for attempting to meddle in Oklahoma politics.

The implicit criticism was that figures like Republican Sens. Ted Cruz of Texas and Mike Lee of Utah had endorsed an establishment moderate.

“Your endorsements have given him the appearance of a grassroots, conservative, liberty loving candidate. While we hold his feet to the fire, you embrace him,” they wrote.

The Tarrance Group poll revealed that Shannon has work to in his effort to beat Lankford in the special election being held to fill the final two years of Coburn’s term. Coburn plans to retire at year’s end, two years before his current term expires. According to the survey, Lankford’s 10-point advantage over Shannon includes these findings:

• A lead 14 percent among seniors,

• A lead of 11 percent among “very fiscally conservative,”

• A lead of 11 percent among “very socially conservative,”

• A lead of 36 percent in the Oklahoma City media market, and

• A lead of 18 percent among those who say they attend church frequently.