[244] In 1949, Truman described American communist leaders, whom his administration was prosecuting, as "traitors",[243] but in 1950 he vetoed the McCarran Internal Security Act. It was passed over his veto.[246] Truman would later state in private conversations with friends that his creation of a loyalty program had been a "terrible" mistake.[247]

Blair House and assassination attempt
Main articles: White House Reconstruction and Attempted assassination of Harry S. Truman
View of the interior shell of the White House during renovation in 1950
In 1948, Truman ordered an addition to the exterior of the White House: a second-floor balcony in the south portico, which came to be known as the Truman Balcony. The addition was unpopular. Some said it spoiled the appearance of the south facade, but it gave the First Family more living space.[248][249] [250] Meanwhile, structural deterioration and a near-imminent collapse of the White House led to a comprehensive dismantling and rebuilding of the building's interior from 1949 to 1952. Architectural and engineering investigations during 1948 deemed it unsafe for occupancy. President Harry S. Truman, his family, and the entire residence staff were relocated across the street into Blair House during the renovations. 