AN ECONOMIST IS SITTING IN THE OVAL OFFICE OF THE WHITE HOUSE, ACROSS THE DESK FROM THE PRRESIDENT OF THE UNITED STATES.THE PRESIDENT ASKS,...

I am assuming that by "foreign income" you mean the income of people in foreign countries.  Here's how that works:

Many of the things the US produces for export are high cost items.  We are talking here about things like Microsoft Office, for example.  Because of this, US exporters need people in other countries to get richer so they can afford our products.

So, if income does not grow in other countries, they are able to demand fewer American goods.  When this happens, American companies (that rely on exports) might have to lay people off or forego hiring new people.  Either way, it won't help employment.