As for Congress, Republicans have a virtual lock on the House of Representatives, so a reelected President Obama would confront at least one chamber whose leaders oppose him. On the Senate side, a President Romney would face either a Democratic majority or a narrow GOP majority subject to Democratic filibuster.
Mandates are rare. The last presidential election that resulted in all three conditions was 1964. And in the record books, there is an asterisk next to that one. Democrat Lyndon Johnson ran as the peace candidate, but he already knew that the situation in Vietnam was getting worse. As a result, a bitter joke arose in the mid-1960s: “They told me that if I voted for Goldwater, we’d have a war in Vietnam. They were right. I voted for Goldwater, and we had a war in Vietnam.”
Of course, our definition of “mandate” might be too narrow. If we relax the second condition about the popular vote, we might find mandates in the elections of 2004 and 2008. George W. Bush’s margin against John Kerry was narrow but his share of the popular vote was the biggest since his father’s election in 1988. Obama had an even greater triumph against John McCain, albeit with a slightly smaller share of the popular and electoral vote than the elder Bush.