Jim DeMint is being forced out as the leader of the conservative Heritage Foundation think tank amid internal tensions at the organization over its direction, several sources have confirmed to Fox News.

The former South Carolina Republican senator's imminent departure was first reported late last week and has since sparked widespread speculation about what led to the separation.

Several sources have said the end of DeMint’s roughly four-year term was driven by Michael Needham, chief executive of Heritage’s advocacy group, Heritage Action for America.

Needham complained to Heritage’s board of trustees that the foundation under DeMint was becoming too political with its outreach and messaging -- not on its founding mission of crafting conservative policy -- especially when Heritage Action was created in 2010 for such purposes, sources said.

Needham has declined to discuss the matter but praised DeMint on “Fox News Sunday” as a “patriot.”

“I'm not going to add to the speculation and rumor,” Needham said. “The Heritage Foundation is an institution that is committed to formulating and promoting conservative policies. And that is not going to change.”

Still, a wide range of other explanations have emerged beyond the purported rift, timed as DeMint’s contract, which includes an estimated $1 million-plus annual salary, ends in December.

Among them is that wealthy Heritage board member Rebekah Mercer wants to replace DeMint with her political adviser and film business partner Steve Bannon, now President Trump’s chief White House strategist.

Ed Feulner, a former Heritage president, reportedly would replace DeMint, 65, at least in the interim.

Another explanation for the split is that DeMint strayed from conservative principles by getting too close to the populist-styled Trump -- while others, to the contrary, say his ideological purity on repealing ObamaCare thwarted a victory for fiscal conservatives and a major Trump campaign promise.

Heritage, though, helped deliver a major victory for conservatives with the nomination and confirmation of Judge Neil Gorsuch to the Supreme Court.

“I just can’t see where getting close to an administration would be a particularly bad thing,” Rob Carter, a member of the Maryland Republican Party, told Fox News on Monday. “Still, people come and go in Washington. Sometimes it’s a popularity contest, not a meritocracy. Boards make decisions based on the now. The king is dead; long live the king.”

DeMint is considered a founding member of the roughly eight-year-old Tea Party movement, which helped Republicans take the House in 2010 and then continued to back challengers in GOP primaries in which incumbents were deemed not conservative enough.

Republican Sens. Rand Paul, of Kentucky; Mike Lee, of Utah; and Ted Cruz, of Texas, are among those the movement helped get elected.

DeMint came to Washington in 1999 as a House member and was elected to the Senate in 2004. He resigned from the Senate in 2013 to run the roughly 34-year-old foundation.