A new internal poll conducted for Sen. Lamar Alexander’s (R-Tenn.) campaign shows him with a hefty lead over his closest Republican primary challenger, state Rep. Joe Carr.

The survey, conducted by North Star Opinion Research and obtained by The Hill, gives Alexander 56 percent to Carr’s 14 percent support among likely GOP primary voters in a full ballot test. 

The other six primary challengers tested take no more than 2 percent each, and 22 percent are undecided.

It’s a slight reduction in support for Alexander from his last internal poll, conducted in February, when 62 percent of likely GOP primary voters backed him in a head-to-head contest with Carr. But Carr has lost support since — he took 17 percent support.

The survey also shows that Alexander's challengers have so far failed to make much more than a blip on the radar of the GOP primary electorate. Sixty-seven percent of primary voters haven’t heard of Carr, who hasn’t improved his name recognition much since February, when he was unknown to 70 percent.

The rest of Alexander's challengers are unknown by 80 percent or more of the electorate.

Still, Tennessee’s early August primary is one of the latest in the nation, meaning Alexander’s opponents still have time to move the needle, but the new survey indicates they have a steep hill to climb.

It’s also unclear what holes in Alexander’s support they’d be able to take advantage of. The new survey shows Alexander’s approval rating at 66 percent statewide, with 26 percent disapproving of his performance.

North Star Opinion Research President Whit Ayres wrote in the memo that the new survey indicates there’s been very little movement in the race.

"This campaign looks essentially the same today as it did in August of 2013 and February of this year. Senator Alexander remains in a very strong position to win the Republican nomination for U.S. Senate,” he said.

The survey was conducted among 600 likely GOP primary voters from May 12-14 via landline and cellphone, and it has a margin of error of plus or minus 4 percentage points.