A while back, I wrote here about the North Carolina Senate race between Republican incumbent Elizabeth Dole and Democrat Kay Hagan.
In August, I wrote that Dole had a definite, but not huge, lead. The latest polls show a very close race, with a bit of an advantage for Hagan.
When Republicans projected a loss of four-to-five Senate seats this year, I don't think they were including the North Carolina contest in that number. If more such seats drift toward the Democratic column, that party could reach the magic number of 60.
As I wrote in more detail here, 60 votes are required to invoke the cloture rule, and end a filibuster. If, as current polls indicate, the Democrats win the presidency, and maintain their majority in the federal House of Representatives, the filibuster would be the Republicans' only weapon to impede the enactment of Democratic initiatives.
Sixty Senate seats would give the Democrats a monopoly on power that neither party has exercised since the Democratic-controlled "Great Society" Congress of 1965-66.
CORRECTION: My history lesson is faulty. In 1977 and 1978, the Democrats also controlled the White House and the House of Representatives, and had enough senators to invoke cloture. There were 61 Democratic senators, just two years after the cloture rule was amended to allow three-fifths of the total number of senators to invoke cloture. However, Jimmy Carter was not as successful during the 1977-78 Congress, as Lyndon Johnson had been during the 1965-66 Congress, in getting his legislation enacted. That was probably because the Carter Administration with its "outsider" culture found itself feuding with congressional Democrats about as much as it opposed congressional Republicans.