The popular EB-5 program, which grants visas and--perhaps more significantly--helps bankroll huge developments all over the nation, is under fire from California Sen. Dianne Feinstein, calling "deeply unfair" and "susceptible to fraud and abuse."

The number of visas issued from 2011 to 2014 increased by about 6,000. In the last year alone, developers have raised over a billion dollars, mainly from Chinese investors, to erect stunning projects.

Feinstein says the program gives an unfair citizenship advantage to foreigners with deep pockets, while an estimated 4.4 million are "unable to buy their way into the country," and are stuck in visa backlogs for up to 23 years, her letter says.

"Simply put, EB-5 sends a terrible message to the millions of immigrants patiently waiting their turn to enter the United States legally to be reunited with their families or for legitimate employment," she says.

She also questions the legitimacy of those investors, with some getting caught illegally raising millions of dollars. Unless there are steps to reduce fraud, Feinstein will call for an end to the program. Congress has until December to decide its fate.