"Leaders keep their eye on each other, but they try to stay away from each other's national politics," said Stephen Hess, a presidential scholar at the Brookings Institution.
In campaign speeches, Romney frequently claims Obama has turned his back on Israel and is too soft on Iran.
Yet despite their policy disagreements, the two rivals seem to be saying roughly the same thing on the subject of a "red line."
Obama says his red line is "that we're not going to accept Iran having a nuclear weapon," without being more specific. And Romney says, "My red line is Iran may not have a nuclear weapon."
Anthony Cordesman, a Middle East expert at the Center for Strategic and International Studies, said, "You have two presidential candidates working away to see who can get the most votes, and an Israeli prime minister working to figure out how to get the most American support."
Netanyahu claims Iran is six months to seven months away from having 90 percent of the ingredients for a nuclear bomb. White House spokesman Josh Earnest said that Obama "does believe that there is a diplomatic window that remains open to preventing that red line from being crossed."
AP writer Amy Teibel in Jerusalem contributed.
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