Just before U.S. Sen.-elect Ruben Gallego formally declared victory over Republican rival Kari Lake, one of her allies posted on social media a message hinting at something amiss in the race.

Kari Lake spoke at CPAC about combating misinformation with truth. Yet Lake repeated a debunked claim by Elon Musk that Social Security sends benefits to 150-year-olds. Lake also said she had ...