In 2010, Fiorina's Senate campaign was severely undermined by a series of attack ads that emphasized her failure as a Hewlett-Packard CEO. Could this happen again? Carly Fiorina is doing well in polls. As Donald Trump saw his support drastically diminish following the second GOP debate, the businesswoman swiftly rose to No. 2 with 15 percent of Republican support. But critics are skeptical that her success will persist. The reason? Her dismal tenure as CEO of Hewlett-Packard from 1999 to 2005, during which 30,000 employees were laid off. In 2010, Mrs. Fiorina ran for Senate in California, against Democratic incumbent...