US History Trivia: What US President had the Secret Service codename of Lancer?

The U.S. Secret Service has been protecting Presidents since 1902, first protecting Theodore Roosevelt in the aftermath of three Presidential assassinations in a forty year span.  The service has given President's code names by which they are referred to, and these names can be subject to much interest from the general public.  So, off of Pocket Trivia: US History - What US President had the Secret Service codename of Lancer?  Was it Theodore Roosevelt, Richard Nixon, John F. Kennedy or Franklin Roosevelt?

US Presidents Trivia: What President was not allowed to attend his party's national convention by the Secret Service?

One of the highlights of virtually every Presidential nominating convention is speeches by the incumbent President or former President's.  With relatively few exceptions (2008 being one of them), former/current President's are welcomed with open arms and seen as rallying points for their party.  However, this isn't always the case - in some cases, President's are unpopular and seen as relics of the past.  And in at least one case, the Secret Service refused to allow a President to attend his party's nominating convention due to fears on his life.  So, off of Pocket Trivia: US Presidents - What President was not allowed to attend his party's national convention by the Secret Service?  Was it Abraham Lincoln, John Kennedy, Lyndon Johnson or Woodrow Wilson?