Trump’s pledge that he won’t try to oust House Speaker Paul Ryan or Senate Majority Leader Mitch McConnell was a key factor in the decision by coal industry executives Joe and Kelly Craft to raise money for the presumptive Republican presidential nominee, they say.

“That is a big priority for Joe and I—and from talking directly to Donald Trump I know for a fact it is a big deal to him,” Kelly Knight Craft, a Kentucky native, said in an interview. “He made that very clear.”

The reassurances are a window into Trump’s effort to convince establishment Republicans that he’s not trying to hijack the party’s infrastructure and that he’ll cooperate with other party leaders if elected president…

“When someone gives us a check, we’re looking at that as they’re investing not only in that candidate—investing in Paul Ryan or investing in Mitch McConnell or investing in Donald Trump—they’re investing in us, and I take that as a responsibility. I don’t take that lightly. We feel responsible to them,” she said.