U.S. President Ronald Reagan (1911-2004) addressed the annual Gridiron Club dinner (usually a humorous occasion) in Washington, DC, both in 1986 and in 1988, saying:
 
“Before I refuse to take your questions, I have an opening statement.”
   
Reagan’s joke is often cited by politicians who refuse to take questions from the press.
 
   
Wikipedia: Ronald Reagan
Ronald Wilson Reagan ( /ˈrɒnəld ˈwɪlsən ˈreɪɡən/; February 6, 1911 – June 5, 2004) was the 40th President of the United States (1981–89). Prior to that, he was the 33rd Governor of California (1967–75), and a radio, film and television actor.
 
25 March 1986, Richmond (VA) Times-Dispatch,  “The humorists of Washington” by Charles McDowell, pg. B1, col. 1:
President Reagan: “Before I refuse to take questions, I have an opening statement.”
(President Ronald Reagan at the Gridiron Club dinner—ed.)
 
4 April 1988, San Jose (CA) Mercury News, “Congress, Reagan rid selves of Contra liability,” pg. 5B:
Addressing the annual Gridiron Club dinner March 26, the president said, “Before I refuse to take your questions, I have an opening statement.”
 
Google News Archive
3 January 1989, The Telegraph (Nashua, NH), “It was a wonderful year for Reaganisms” by Lou Cannon, pg. 14, col. 4:
For his part,  Reagan tried not to get too close to the media. He held only four new conferences in 1988, and on March 26 opened his speech to the Gridiron Club by saying, “Before I refuse to take your questions, I have an opening statement.”
 
25 April 2006, Daily Herald (Chicago, IL), “A few thoughts, from Martin Short to Donald Trump” by Mark Shields, sec. 1, pg. 12, col. 4:
The Bush administration’s ideal new White House press secretary would begin the daily reporters’ briefing this way: “Before I refuse to answer any questions, I have an opening statement.”
     
Google Books
Communication!:
A Radically New Approach to Life’s Most Perplexing Problem
By Lee Thayer
Xlibris Corporation (Xlibris.com)
2009
Pg. 222:
Kings and presidents cling to the prerogative of avoiding a dialog by insisting on their right to a mnoolog. Or, as Ronald Reagan once put it in a speech in 1989:
 
“Before I refuse to take your questions, I have an opening statement.”
 
The Spokesman-Review (Spokane, WA)
September 11, 2011 in Opinion
Smart Bombs: They’re no Ronald Reagan
Gary Crooks
(...)
Projecting. Speaking of Reagan, Spokane Mayor Mary Verner should’ve borrowed one of his quotes for Friday’s press conference: “Before I refuse to take your questions, I have an opening statement.”