This is not unexpected. There was an incredible flurry of high winds from January through May, propelled by the jet stream of primary activity (to continue the nautical analogy). Now there is no jet stream. Looking to the horizon, we expect the winds, perhaps of hurricane force, to pick up as we approach the conventions. But we don't see signs of them now.
This isn't to say that the campaigns aren't attempting to turn up the wind machines. No doubt, each campaign is haunted by the specter of Michael Dukakis in 1988. Upon receiving the Democratic nomination at the convention in July, Dukakis returned home to Massachusetts to attend to being governor. That was fine in principle. But his absence from the presidential campaign trail was coincident with a total evaporation of a 17-percentage point post convention lead over George H.W. Bush that Dukakis enjoyed immediately after the Democratic convention. So, Dukakis dutifully toiled away in Boston. The GOP held its own convention in August. Bush emerged with an eight-point lead by early September. As you will remember, Bush won the election in November.
So neither campaign is allowing its candidate to rest. Barack Obama and John McCain are campaigning ceaselessly. The news media are doing their part, breathlessly looking for any morsel of campaign news to report on. Indeed, campaign news still fronts the newspapers, leads newscasts, and is the dominant talk on cable news shows.
The campaigns may argue that the real purpose of their campaigning at this point is not to change voters' minds, but to lay the groundwork of "brand positioning" for their candidate so that he is better able to withstand the inevitable battles to come.
If that's the case, then we won't know the results of the effort until later this summer and fall. Voters at this point simply aren't changing their minds. Our Gallup Poll Daily tracking essentially shows no substantive or structural change in the standing of the two candidates in our trial heat measures for more than a month now.