In July he went backward. Negative impressions now outweigh positive impressions by 15 percentage points — 52 to 37 percent. A month ago, the difference was just six points. The poll was completed just as Romney’s foreign trip was starting…

Romney is above 50 percent positive in the Pew findings with only two groups: Republicans and white evangelical Protestants. He is at 32 percent favorable among women; 38 percent with college graduates; and just 40 percent among those with incomes above $75,000. Among independents, he is at 41 percent positive.

Romney advisers say the deterioration between June and July is mostly with people who were not going to vote for Romney anyway, which they say worries them less than if they were losing ground again with their core voters. They argue that Obama threw tens of millions of dollars worth of ads at Romney on Bain Capital, outsourcing and tax returns and that it didn’t dramatically change the race.

That still leaves Romney with historically low personal-image numbers as he heads toward the fall. Maybe that matters less than it once did, but it’s hardly an ideal situation for the challenger…

The candidate needs a fresh look from the voters. He has unveiled new ads and a new focus on the middle class. But his vice-presidential pick will be the first real moment for that fresh look to take place