Rep. Jack Kingston (R-Ga.) has a big lead over businessman David Perdue (R), according to an internal poll released by Kingston's campaign.

Kingston leads Perdue by 49 percent to 35 percent in to a live-caller poll conducted by McLaughlin & Associates for Kingston's campaign, the latest sign the congressman has the momentum heading into their July 22 primary runoff.

Internal polls should always be viewed with some skepticism, as they often are released to boost a candidate's standing. But these numbers are close to what two other recent polls of the race have found: That after trailing Perdue in the first round of voting, Kingston has built up a double-digit lead.

Kingston has also been rolling out a number of big-name endorsements in recent weeks. The latest comes from former House Speaker Newt Gingrich (R-Ga.), who backed him Tuesday morning.

The live-caller survey of 500 likely GOP primary runoff voters, including 100 who only have cell phones, was conducted from May 27-29 and has a margin of error of plus or minus 4.5 percent.