President Donald Trump's proposed $5 million "gold card" for U.S. residency would be one the most expensive in the world, according to experts.

President Donald Trump's commerce secretary, Howard Lutnick, claimed the "Gold Card" visa program already has 250,000 applicants.

Estimates of how many millionaires could afford to buy Trump's proposed visa range from 1.5 to 3.3 million people, according to recent reports.

Trump’s rationale ranges from raising money to pay for tax cuts to bringing back manufacturing to the U.S. to leveraging concessions from trading partners, and the idea has raised concerns about a global trade war. Rates as high as 25% on goods from Mexico and Canada, for example, are slated to go into effect March 4.