Sen. Ron Johnson (R-Wis.) said this morning that a former Hillary Clinton staffer will be offered immunity from prosecution in exchange for testimony on her private email server. 

Bryan Pagliano, who set up the server in Clinton’s home in 2008, said last week he would invoke the Fifth Amendment if he is called to testify before Congress.

Johnson and Sen. Chuck Grassley (R-Iowa) now say Pagliano will be offered immunity by their respective committees. 

Johnson said on "America's Newsroom" they cannot compel Pagliano to testify and would like to meet with Pagliano's lawyers first to determine what sort of information he has. 

He said the Senate has no interest in going after Pagliano. 

"I'm concerned about the national security implications of what Secretary Clinton did," said Johnson, adding that Clinton is not the only administration official accused of using private email in order to shield information from FOIA requests.

Johnson said he believes the Obama administration has been "the most opaque" in history. 

In an interview with ABC News that aired last night, Clinton apologized for using the private server while she was secretary of state.