Conventional wisdom holds that President Obama is focusing just enough attention on North Carolina to ensure that Republican challenger Mitt Romney has to devote more resources in this state than in places such as Ohio and Florida.

But what if the president is forced to do some unexpected campaign spending of his own? Michael Barone explores that possibility in his latest Washington Examiner blog entry.

Why would the Obama campaign want to advertise in Oregon? It’s a state where public polling shows him Obama ahead of Mitt Romney—by 50%-41% in a September USAToday poll and 50%-42% in a Public Policy Polling poll in June. Obama carried Oregon 57%-40% in 2008, much better than John Kerry’s 51%-47% in 2004. In 2000 it was really close: Al Gore carried it over George W. Bush, 47%-47% (47.0%-46.5%), while 5% of the vote for Ralph Nader.

In other words, in two of the last three presidential elections Republicans got 47% of the vote and, when a left-wing third party candidate got 5% of the vote, the Republican candidate almost carried its 7 electoral votes. In 2010 Democrat John Kitzhaber won the governorship by only a 49%-48% margin; Republicans won a 60-60 tie in the state House and Democrats held on to only a 16-14 margin in the state Senate. So at least in 2010 Republicans were getting close to 50%. In 2010 elections to the U.S. House in Oregon Democrats, who held four of the five seats, won 51% of the votes to 46% for Republicans.

My guess: someone in the Obama campaign somewhere are concerned that Libertarian party nominee Gary Johnson may cut into Obama’s vote in Oregon, which could make Mitt Romney competitive as George W. Bush was in 2000. After 2000 many left-leaning voters were wary of third party candidates like Nader, for fear that votes for them would elect a Republican. But Johnson differs from Nader in one important way: the former governor of New Mexico favors liberalizing the laws against marijuana. If you’ve read Mark Hemingway’s March 2012 Weekly Standard cover story entitled “Insufferable Portland,” you may have developed a suspicion, as I have, that Portland has more than its proportionate share of pot-loving voters. Is the Obama campaign afraid they’ll desert to Gary Johnson?