Lyndon Johnson had sex with pretty, blonde Hearst reporter Cassie Mackin who covered him as early as the 1960 campaign

 Mack White: Lyndon Johnson had sex with Hearst reporter Cassie Mackin, a young pretty, educated blonde

Mack White, now an acclaimed comics cartoonist, used to transcribe oral histories at the LBJ Library.

Mack White email to Robert Morrow on Oct. 9, 2015:

QUOTE

Hi, Robert! As I wrote on my FB post, she did not actually say she was a mistress; I had to put two and two together. Not difficult, but without an outright admission on her part I would be reluctant to name her ... However, if you'd like a name, I can tell you that NBC reporter Cassie Mackin was a paramour of LBJ's. 

This was described in one of the oral histories I transcribed; the interview was with a male colleague of hers. This would be on file at the LBJ Library. Unfortunately, after all these years, I can't remember the name of the interviewee, so it would take some research at the library to find it. And it might still be classified ... It's great hearing from you, Robert. I've been following your research and am interested in this new book you co-authored with Roger Stone. Please stay in touch ... Mack

 UNQUOTE

 Cassie Mackin Wiki: https://en.wikipedia.org/wiki/Catherine_Mackin

Mack White email to Robert Morrow on Oct. 9, 2015

QUOTE

Yes, anything that moved was fair game for Lyndon ... Cassie Mackin covered his 1960 campaign, which indicates they went way back, before the tryst during his presidency (described in the oral history).

 UNQUOTE

 Mack White is Texas born comics writer and artist who used work at the LBJ Library: https://en.wikipedia.org/wiki/Mack_White

 Cassie Mackin (1939-1982) was a tall, slender, pretty blonde reporter who reported for Hearst papers from 1963 to 1969. Hearst papers were a media venue that was very friendly to Lyndon Johnson. Ed Weisl, the legal counsel for Hearst was one of LBJ’s most critical Wall Street fundraisers for decades. https://en.wikipedia.org/wiki/Catherine_Mackin Sadly, Cassie Mackin died of cancer at the age of 43.

 Here is Cassie Mackin on the Dick Cavett show: https://www.youtube.com/watch?v=o9BDQvRBrss

 1982 Washington Post obituary for Cassie Mackin: https://www.washingtonpost.com/archive/local/1982/11/21/catherine-mackin-dies/f217914a-55a5-492d-ab4a-f7c92f46c899/

We certainly know LBJ was physically near Cassie Mackin on 11/2/1965: https://discoverlbj.org/solr-search?q=telephone&facet=51_s%3A%22Text%22+AND+40_s%3A%221965-11-02%22

 Lady Bird Johnson's Daily Diary entry, 11/2/1965 (Item)

·        and returned to Ranch. 11:15 Returned 2. 1:30 President arrived with Cassie Mackin, Muriel Dobbins, Jack Horner, Forest Boyd, Merriman Smith, Frank Larimer, Bill Moyers 2:00 Lunch with above and Jake and Marie 3. 5:00 Had the four telephone operators out

Photos of Cassie Mackin: https://www.google.com/search?q=lyndon+Johnson+cassie+mackin&rlz=1C1GGRV_enUS751US751&sxsrf=ALiCzsYgP-RNLj9lsGO7-o6w_2OkfEkpfA:1667221074685&source=lnms&tbm=isch&sa=X&ved=2ahUKEwilqqy_wor7AhUEoFsKHS_LDioQ_AUoAXoECAEQAw&biw=1280&bih=913&dpr=1