Former White House Chief Strategist Steve Bannon warned this week that there will be a “civil war” in the Republican Party if GOP lawmakers cave on the repeal of an Obama-era program that gave amnesty to illegal immigrants brought to the U.S. as children.

Attorney General Jeff Sessions announced Tuesday that DACA — Deferred Action for Childhood Arrivals — would be repealed with a six-month window for Congress to act. The move served to fulfill one of Trump’s signature campaign promises, but both Trump and Republican leadership have indicated a desire to “legalize DACA” as part of a broader immigration reform bill.

In an interview for 60 Minutes that aired Sunday, Bannon told CBS anchor Charlie Rose that caving on the campaign promise could spell disaster for Republicans and spark a full-blown civil war with its conservative base:

I’m worried about losing the House now because of this … because of DACA. And my fear is that with this six months down range, if we have another huge — if this goes all the way down to its logical conclusion, in February and March it will be a civil war inside the Republican party that will be every bit as vitriolic as 2013. And to me, doing that in the springboard of primary season for 2018 is extremely unwise.

House Speaker Paul Ryan (R-WI) had hoped that Trump would not repeal DACA and has since expressed hope that a compromise can be reached. Trump meanwhile has said that he hopes for a deal where “everybody is happy.”

“I’d like to see something where we have good border security, and we have a great DACA transaction where everybody is happy and now they don’t have to worry about it anymore,” Trump said on Air Force One.

In the interview, Bannon — who has since retaken his role as Executive Chairman of Breitbart News — said he thinks that, instead of focusing on illegal immigrants, the administration should instead be focusing on American citizens.

“I think what we have to do is focus on the American citizens. I think we have to focus on American citizens,” he said.

Bannon went on to say that he would let the work permits expire: “There’s no path to citizenship, no path to a green card, and no amnesty. Amnesty is non-negotiable.”

Adam Shaw is a Breitbart News politics reporter based in New York. Follow Adam on Twitter: @AdamShawNY.