Former Arkansas governor Mike Huckabee (R) and the Senate Conservatives Fund are on opposite sides of the runoff campaign between Rep. Ralph Hall (R-Tex.) and former U.S. attorney John Ratcliffe (R). The conservative group threw its support behind Ratcliffe a day after Huckabee offered his support for Hall.

"John Ratcliffe is a principled, conservative leader who will fight to stop the massive spending and debt in Washington that are bankrupting our country," said Senate Conservatives Fund executive director Matt Hoskins in a Friday statement. "He's part of a new generation of conservative Republicans, and we're excited to support him." Founded as an organization geared toward Senate races, the group has decided to play in House races this cycle, too.

Huckabee announced his support for Hall on Thursday. "Ralph Hall is a statesman, a veteran and a true conservative who will stand up for what’s right. His wisdom, leadership and sound judgment are exactly what we need in Washington, especially now," he said in a statement.

The oldest member of Congress, Hall, 90, is in a tough political fight. He failed to get a majority of the vote in the March primary, triggering a May 27 runoff with Ratcliffe.

Ratcliffe is also backed by the anti-tax Club for Growth. Huckabee and the Club for Growth do not get along.