Create a program for companies that hire H1B visa workers to allow American citizens to job shadow and learn the high demand skills necessary for the job. The program would ask companies to dedicate at least 1 hour of job shadow for every 8 hours worked by the H1B visa worker.
As an incentive for companies to create the program, the white house could publish a list of companies that are participating with more than 50% of their H1B filled positions, and profile success stories of American workers that got trained and hired on in a similar role.