Complex sentence: No public announcement about the serious structural problems of the White House was made until after the 1948 election had been won, by which time Truman had been informed that his new balcony was the only part of the building that was sound.
Split into simpler sentences: No public announcement about the serious structural problems of the White House was made until after the 1948 election had been won. By then Truman had been informed that his new balcony was the only part of the building that was sound.