This will sort of being by backtracking a slight bit. It also kind of skips June 5th to July 9th a bit. I'm guessing others will have to work on that.
April 10th, 1968: Hoping to help secure MLK's support, while not completely abandoning Vietnam, Johnson and Humphrey agree to slightly cool down major American offensives for the next few months at least until the DNC, and instead seek a strategy of defense and securing all currently occupied territory.
April 15th, 1968: Viet-Cong forces begin planning a new offensive, hoping to take advantage of some weakness in the new strategy employed by American forces. This offensive would later be called by some as the Second Tet Offensive.
July 9th, 1968: Humphrey, hopeful to gain MLK's support, begins to speak on how he plans to handle the end of the Vietnam War, declaring, "The death of our boys is nearing it's end. Victory is at hand."
July 12th, 1968: The surprising new second Tet Offensive launches to great success, using both sabotage and forces dung deep within American lines to force a surprise attack with devastating effect. Though not as great a success for the Viet Cong as the first Tet Offensive, it none the less proved a huge embarrassment for Johnson and Humphrey, especially the later, who received much of the blame as he had begun making it a major point in his campaign in the recent weeks that he was taking on many of the Vice President's duties, as well as his earlier declaration a few days before, which was now being compared to Chamberlain's infamous line, "Peace in our time".
July 13th, 1968: Humphrey begins to dramatically slide down in the polls, while some of his opponents such as RFK and Nixon see massive boosts in their own polling.
July 17th, 1968: A flustered Johnson and Humphrey agree to abandon the strategy of defense, and begin doubling down on offensive attacks on the Viet Cong. This results in even more American lives lost and further angers many of the anti-war movement on the homefront.