Gov. Gavin Newsom of California continued his show of support for President Biden on Saturday, praising the Biden administration’s track record in front of an enthusiastic crowd of Pennsylvania Democrats who appeared to remain firmly behind the president despite rising calls for him to leave the race. Newsom’s optimism and his message of Mr. Biden’s proven success were welcomed by the crowd in Doylestown, Pa. Many in attendance said they were tired of the discussion over whether the president should continue his campaign — even staunch supporters of Mr. Newsom, who is considered a potential replacement for Mr. Biden atop...