An influential Republican senator is trying to sow seeds of doubt about a program suspending deportation for certain illegal immigrants, even as Republicans elsewhere in Congress have lined up to implore President Trump not to cancel it.

The office of Senate Judiciary Committee Chairman Charles E. Grassley (R-Iowa) released data from U.S. Citizenship and Immigration Services (USCIS) on Friday afternoon showing that "thousands" of beneficiaries of the Deferred Action for Childhood Arrivals, or DACA, program had managed "to exploit an immigration law loophole to obtain green cards" with the Obama administration's permission. And for some, the senator's office says, that loophole has already led to citizenship.

"The DACA program was never intended to provide a pathway to citizenship," Grassley's office wrote, noting that "the program's legal future is in jeopardy."

Grassley's data drop comes as Washington is waiting for an expected Tuesday announcement from Trump about the future of the Obama-instituted DACA program.

The program, enacted in June 2012, has given about 800,000 undocumented immigrants a chance to live, study and work in the United States without fear of deportation, following an application and screening process.

Most Republicans who spoke about the DACA program Friday — including House Speaker Paul D. Ryan (R-Wis.) — opposed dismantling it. Speaking on WCLO, a radio station in his home town, Ryan said that Trump should leave DACA alone, though he added that it "is something that Congress has to fix."

Grassley's office struck a different tone, focusing on the 1,056 DACA beneficiaries who it says managed to turn their deferred status into citizenship.

The "loophole" that Grassley's office points to involves a feature of the program known as "advance parole" that allows DACA recipients to travel back to their home country and then return to the United States. That permission is granted only in limited circumstances: for humanitarian, education or employment-related purposes. According to the USCIS figures Grassley's office cited, 45,447 DACA recipients have been approved for advance parole.

But Grassley's office says a DACA recipient who has been awarded advance parole is technically entering the country legally when they return from their approved overseas travel. That opens up the possibility for some to apply for adjusted legal status, such as the lawful permanent residency that gets them "green card" status.

Grassley's office says the USCIS data indicates 59,778 DACA recipients applied for green card status, and that 39,514 were approved.

Green card recipients are eligible to apply for U.S. citizenship after five years, but citizenship is not guaranteed.

Grassley's committee and the House Judiciary Committee acquired the data after making inquiries to USCIS. The data covers a period from the inception of the DACA program through Aug. 21 of this year.

DACA allows immigrants who entered the United States illegally as minors to avoid deportation for two years and be allowed to apply for work permits. After two years, someone granted DACA can apply for renewal. President Barack Obama announced DACA on June 15, 2012, and the USCIS began accepting applications two months later.

As a candidate, Donald Trump promised to end the program, though recent reports suggest the president may opt to phase it out instead. But since taking office, the president has adopted softer rhetoric toward beneficiaries of the program, saying he wants to treat them "with heart" and that he thinks "the dreamers are terrific."