How did the Tet Offensive affect public opinion about the Vietnam War?

On January 31, 1968 — the Vietnamese New Year, called "Tet," — communist forces unleashed massive attacks on U.S. positions throughout Vietnam. The Tet Offensive, televised nightly in the U.S., shocked many Americans who previously had the idea the U.S. was easily taking care of the enemy. U.S. forces eventually pushed the North Vietnamese forces back and inflicted huge casualties on them, but the impact the fighting had on U.S. public opinion was equally huge. Opposition to the war grew more heated and contributed mightily to Lyndon Johnson's decision not to run for re-election in 1968.