Paula White, the prosperity gospel preacher charged as Donald Trump's chief spiritual adviser, is taking 'care of his soul' not his rhetoric, her husband has said.

Rock and roll legend Jonathan Cain said his wife has been called by God to pastor Trump in Washington.

'Paula's in there doing the best she can do and taking care of his soul. Not his politics. Not his rhetoric. His soul,' Cain said in an interview with the Tennessean. 'If he leans on her for that, that's a good thing. That is a really good thing. She brings prayer into the White House. I think it's remarkable. I applaud her tenacity and it hasn't been easy watching her get yanked around by the swamp and yet she prevails. She'll overcome.'

Cain married White after two previous marriages failed and praised her for her role in the White House.

'It's a calling. She's been called upon, I believe, good or bad. She's been called by the kingdom to serve. She is letting grace in the door in Washington and I've seen it, uttering the name of Jesus Christ on the mall of Washington. It's amazing,' he said.

'We have to understand that Paula's there to minister to the president and to pray over him. She's the one he trusts for prayer and she prays over him. And, she brings mighty men of God to pray. Who are we to say the president doesn't need prayer?

'That's what makes me crazy. Let's not judge. Why are we the ones throwing the stones? This is our president and with his faults, with his mistakes, with the things he says, he is our president. We are to honour the authority of our leaders. We are to honour those leaders. They've been chosen by God.'

Earlier this year White attracted controversy after asking people to donate their January salary in order to receive blessings, or face divine consequences.

In a video on her website, White, who heads up the president's evangelical advisory committee and is pastor at the megachurch New Destiny Christian Center, in Apopka, Florida, suggested making a New Year donation to her ministries.

White said this was to honour the religious principle of 'first fruit,' which she said is the idea that all firsts belong to God, including the first harvest – and the first month of people's salaries.

'Right now I want you to click on that button, and I want you to honour God with his first fruits offering,' she said in the video.

'If God doesn't divinely step in and intervene, I don't know what you're going to face – he does,' she said.