Wednesday’s Gallup poll had President Barack Obama and Mitt Romney essentially tied, with Mr. Obama at 47% and Mr. Romney at 46%. That’s good news for the challenger: Mr. Romney has absorbed a punishing three-month Obama television barrage that drained the incumbent’s war chest. Historically, undecided voters tend to break late for the challenger.

Mr. Romney and his campaign have also raised their game. After Mr. Obama declared on July 13 that “If you’ve got a business, you didn’t build that,” Mr. Romney went on offense, saying the following Tuesday in Pennsylvania that the notion entrepreneurs didn’t build their businesses was “insulting.” Wednesday in Ohio, Mr. Romney attacked Mr. Obama for not having met with his Jobs Council for six months. Thursday in Massachusetts, Mr. Romney belittled the White House’s explanation that the president had failed to do so because he “has a lot on his plate.” The following Tuesday in Nevada before the Veterans of Foreign Wars, Mr. Romney criticized Mr. Obama over cuts in defense and veterans care…

And then there is Mr. Romney’s convention speech, which needs to be powerful. More Americans will watch it than any other election event except the debates. (In 2008, more than 38 million Americans watched the two candidates’ acceptance addresses.) This will be Mr. Romney’s best moment to provide insights into his character, share the values that guide him, and lay out a growth agenda.

Among other things, Mr. Romney should talk about his father’s modest upbringing, his wife’s illness, and his wealth. Americans know nothing about the first, little about the second, and (courtesy of Team Obama) much about the third. Mr. Romney can show more of his personal side, which would reveal a man of enormous decency and good character.