More than any congressional battle in the South, Tuesday’s runoff in North Carolina’s 8th District has become a magnet for money.

Only two districts in the country have seen more outside spending than the $1.6 million poured into the quiet, mostly rural 8th District, which stretches from Cabarrus to Robeson counties.

On Tuesday two groups announced that they’re putting another $750,000 into the runoff.

The YG Action Fund and American Action Network, both independent groups aligned with the GOP’s Washington establishment, announced they’re spending the money on ads for Richard Hudson, a former Capitol Hill staffer.

Hudson faces Scott Keadle, an Iredell County commissioner who has his own deep-pocketed ally.

The Club for Growth has spent nearly $711,000 on his behalf. The Club also has “bundled” contributions of $191,000 – roughly half of all Keadle has raised from individuals.

The Club advocates low taxes and limited government and is often at odds with more mainstream Republicans. It has helped insurgents oust longtime GOP incumbents such as U.S. Sen. Richard Lugar, R-Ind., in primaries. The club was started in 1999 and receives contributions from 75,000 members across the country.

The spending reflects national interest in the district, which Republicans see as one of their top U.S. House pick-up opportunities in November.

One reason: Democratic Rep. Larry Kissell is widely seen as one of his most vulnerable incumbents. Not only have GOP lawmakers made his district more Republican, but recent votes have sparked a backlash from his own party. The district’s Black Leadership Caucus plans to announce a write-in candidate Wednesday night.

All the money is chasing a few votes.

Lots of money; few voters

About 149,000 registered Republicans and 13,700 unaffiliated voters who voted in the May 8 GOP primary will be eligible to vote, said state election director Gary Bartlett, who predicts a turnout from 5 percent to 8 percent.

That would mean barely 13,000 voters decide the race.

But it’s among a handful of House races that will decide which party controls the House, said Bob Beirsack, a senior fellow at the nonpartisan Center for Responsive Politics in Washington, D.C.

That the 8th is largely rural and expects a small turnout means outside groups “can get a bigger bang for the buck,” he said. “You get the attention of major outside groups who have strong views of who the best nominee will be and they are willing to spend significantly.”

The money also reflects the clear political division in the race that pits a Capitol Hill insider and a maverick outsider.

“It’s a clear contest between a conservative who would vote with Republican leadership and an insurgent who might give Republican leaders trouble,” said Dave Wasserman, an analyst with the Cook Political Report.

Hudson was the district director for former U.S. Rep. Robin Hayes of Concord when he represented a far different 8th District. He’s backed by the GOP establishment in North Carolina and Washington.

The YG (for “Young Guns”) Action Fund, aligned with House Majority Eric Cantor, announced it’s putting another $450,000 into the race on Hudson’s behalf, for a total of $525,000.

The American Action Network launched a $300,000 ad campaign Tuesday. The self-described “center-right” group is led by a former political director of the National Republican Congressional Committee.

“Scott Keadle has a troubling record of saying one thing but doing another from Obama’s stimulus to green energy government subsidies,” spokesman Dan Conston said, referring to Keadle’s votes as an Iredell commissioner for county projects.

Hudson said that’s behind the YG’s support, too.

“The Young Guns also have concerns with his stimulus vote,” he said.

Scaring John Boehner

Keadle has become a darling of insurgent conservatives.

A Salisbury dentist who lives in Iredell County, he said the Republican Party’s “establishment” leaders are concerned he’ll be the Republican nominee.

“I vote for the country instead of the Republican Party leadership,” he said. “I have obviously scared the establishment to the point they think they need to try to get rid of me. …

“When (Republican House Speaker) John Boehner and (U.S. Rep.) Eric Cantor get together all the resources they can come up with to try to fight a dentist from Salisbury, you have to wonder why I scare them so much. I know why. They know why. … I’m not for the status quo.”

The Club for Growth has not only supported him through its super PAC, it’s also helped him raise money from people like John Peck Jr., a California-based real estate investor. He looked at the Club’s recommendations on whom to support.

“I’m for anybody who espouses less government, less spending and less taxes, and in particular anybody who’s going to do that aggressively,” he said Tuesday.

The Club for Growth may not be finished investing in the 8th District.

“Stay tuned,” said spokesman Barney Keller.