In Post-Primary Period, Campaigns Race to Define Challenger

...[T]he months between the end of the primary season and the formal start of the general election at the conventions are an especially perilous period for candidates in Mr. Romney’s position....

The risks of failing to win the spring-summer narrative battle are substantial. Just ask Michael Dukakis, Bob Dole or John Kerry, all of whom failed to establish strong positive images during this period and allowed their opponents to brand them in ways they never overcame.

In 1988, Vice President George Bush used Willie Horton starting in June to portray Mr. Dukakis, the Democratic nominee that year, as a soft-on-crime liberal. Mr. Dukakis never really found a way to respond, and was wiped out in November.

In the spring of 1996, President Bill Clinton’s team portrayed Mr. Dole as old and a tool of radical conservatives in Congress like Newt Gingrich. Mr. Dole desperately tried to establish a fresh identity for himself by resigning from the Senate in May, but could not establish a consistent case for his candidacy and was drubbed in the fall....