Business owner Oscar Canales has spent the past three months confined to a church basement in the US city of Greensboro, knowing he could face deportation to El Salvador the moment he steps outside.

Expulsion would mean tearing him apart from his wife and three American children, not to mention shuttering the thriving roofing company he founded which today employs six US citizens.

Canales first came to authorities' attention six years ago, when he was arrested for lacking papers following a minor accident at a traffic light.

But with no criminal record, past administrations chose to overlook the fact he crossed the border illegally in 2005 and issued him work permits that were renewed every year.

Now, he and millions of others are facing expulsion under tough new immigration guidelines instituted by President Donald Trump.

In response, some progressive Christian groups have boosted their efforts to protect vulnerable migrants by exploiting the protected "sanctuary" status of their places of worship while providing shelter and legal aid to would-be deportees.

Canales, who received his deportation order last December, has been living in the United Church of Christ since January 17.

He cannot imagine leaving America. "All my family is here, my wife, my kids," he says, adding he is fearful of being forced to face the violent gangs of a homeland he left long ago.

“They can take one kid and ask for money. If you don't give it today, they can do anything. They can kill people."