The second-ranking GOP senator said several details are not clear on an agreement between President Trump and Democrats to protect illegal immigrants brought to the U.S. as children.

"I think it is an agreement to agree and the details are forthcoming," Sen. John Cornyn, R-Texas, said Thursday.

He was referring to a possible deal that Trump reportedly reached with Democratic leaders over dinner Wednesday night to enshrine protections for illegal immigrants called "dreamers" in exchange for additional border security. However, details remain sketchy on what any deal would entail.

A major point of contention is whether to include a pathway to citizenship for the illegal immigrants affected by the Deferred Action for Childhood Arrivals program. Trump said this month that he plans to end DACA in six months and called for Congress to make a deal to protect them

The Dream Act would provide a pathway to citizenship, but the DACA program does not.

Cornyn said a pathway to citizenship would be an expansion of the DACA program. "That would be something we would have to discuss," he said.

Cornyn added that several questions would have to be addressed in any DACA deal, including chain migration, which is when immigrants bring extended family into the U.S.

"We have to talk about things like chain migration, which is a very big concern, whether they can use this as a way to bring in other collateral family members," he said.