While earmarks may form only a small percentage of the overall federal budget, DeMint said their impact is far greater because they symbolize the kind of backroom deal-making in politics that turns off many Americans.

"They always say, it's just a small amount of money, but earmarks always enlarge our budget and buy votes so that massive bills can go through," he said. Lawmakers can't advocate for spending cuts because "when we direct money back home through earmarks, it makes us complicit in the spending process. It's a killer."

DeMint, who is favored to win reelection against Democrat Alvin Greene, said he considered not running for reelection a year ago because of his frustration with his colleagues in Washington. Instead he started a political action committee to boost more conservative Republican Senate candidates including Rand PaulRandal (Rand) Howard PaulJuan Williams: Counting the votes to remove Trump Mitch McConnell may win the impeachment and lose the Senate GOP threatens to weaponize impeachment witnesses amid standoff MORE in Kentucky, Pat Toomey in Pennsylvania and Marco RubioMarco Antonio RubioApple under pressure to unlock Pensacola shooter's phones Senators offer bill to create alternatives to Huawei in 5G tech Surging Sanders draws fresh scrutiny ahead of debate MORE in Florida.

When asked if there were any current GOP Senators who share his distaste for big government, DeMint could only think of one: conservative firebrand Tom CoburnThomas (Tom) Allen CoburnThe Hill's Morning Report — Presented by PhRMA — Worries grow about political violence as midterms approach President Trump’s war on federal waste American patients face too many hurdles in regard to health-care access MORE (R-Okla.).

"Well, there's Coburn, who has got the courage to go out and make a scene on the floor or to stand up in a conference meeting and stand up to the appropriators. We don't have anyone else," DeMint said.