 -- Two leading U.S. Senators introduced legislation Wednesday night to clean up a boutique U.S. immigration program for wealthy foreigners that has repeatedly been undermined by fraud and in some cases may have been exploited by criminals, money launderers, and foreign agents looking for an easy way across the border.

Senate Judiciary Chairman Charles Grassley, R-Iowa, and Vermont Democrat Sen. Patrick Leahy credited the program, known by the visa designation EB-5, for creating thousands of jobs by offering temporary residency and eventually Green Cards to foreigners who agreed to invest more than $500,000 in approved American ventures. But they also acknowledged what a two-part ABC News investigation found -- that the program had become a magnet for those seeking to sidestep the scrutiny of the traditional immigration process.

“We’ve seen too many occasions where national security has been put at risk and job creation has taken a back seat,” Grassley said. “Our bill strengthens oversight, ensures greater accountability and transparency, discourages fraud, and provides a higher priority for national security.”

Leahy said in a statement released Wednesday night that the “program faces some challenges, but I have not seen any flaw inherent to the program that could not be remedied.”

The two men crafted the legislation in order to fix the program before it was set to expire later this year. Leahy is one of the investor visa idea’s staunchest supporters, while Grassley has been one of its harshest critics. At the heart of the program’s difficulties has been a free-wheeling system that designates privately-run so-called “regional centers” designed to help pair up wealthy foreign investors with entrepreneurs and developers in the U.S.

A Feb. 1, 2013 Homeland Security internal review of the program obtained by ABC News laid out in stark detail the breadth of the troubles afflicting some of the roughly 600 regional centers. The document summarizes 41 investigations, some open and some now closed, into allegations ranging from espionage to fraud to drug trafficking involving investors in various EB-5 investment projects.

One regional center, run by an Iranian-born businessman living in Beverly Hills, continued to be approved to raise roughly $25 million in investment money from foreign sources even when one of his businesses was being raided by agents. Federal officials told ABC News the businessman was suspected of allegedly smuggling banned items to Iran. Lawyers for the company and its owner said they broke no laws.

Another regional center raised money from Chinese investors to finance the construction of federal buildings, including an FBI headquarters building in San Diego, raising what one internal document called “national security concerns” that “pertain to Chinese investors having visibility to FBI blueprints/information.”

DHS officials told ABC News in a statement that the immigration agency “only has the authority to terminate a regional center if there is evidence the center is no longer promoting economic growth -- not on the basis of national security concerns.”

“This lack of discretion limits the ability of the Director or the Secretary to terminate a regional center in the event of suspected or even proven criminal activity,” the statement says, adding that the administration sought additional leeway from Congress to act on security concerns but did not receive it.

The legislation introduced Wednesday attempts to solve that problem by vastly expanding the authority of Homeland Security officials to investigate regional centers for potential fraud or national security concerns, and terminate those that they believe pose a risk to investors or the country. The legislation proposed paying for the increased scrutiny with an “enforcement fund” paid for by the regional centers themselves. It also increases the minimum amount an investor can commit from $500,000 to $800,000 in order to qualify for temporary residency in the U.S.

The legislative proposal also requires enhanced vetting of regional center personnel and screening of applicants with background checks.

Leahy said he pushed forward on the legislation, separate from other immigration measures, because he believes it is important to repair the program before it is set to expire later this year.

Supporters of the program have noted that it is now so popular that the 10,000 visas allotted in 2014 for EB-5 investors were claimed in a matter of months. The money has paid for popular projects -- a Brooklyn basketball arena, a California winery, a Vermont ski lodge, even a Hollywood movie studio -- and it has supported an estimated 42,000 jobs.

"I have seen over the last two decades how the EB-5 program creates jobs and provides access to capital in communities in Vermont and throughout the country, all at no cost to American taxpayers,” Leahy said.