Is this midterm cycle out of the ordinary, or to be expected when during an unpopular presidency?   Gallup takes a look back at the history of its polling and midterm results for Presidents going back to Harry Truman, and notes that unpopular incumbents lose an average of 36 seats in midterm elections:

Presidents who retain majority job approval from Americans at the time of midterm elections are much less likely to see their party suffer heavy seat losses than are those with sub-50% approval ratings. Since 1946, when presidents are above 50% approval, their party loses an average of 14 seats in the U.S. House in the midterm elections, compared with an average loss of 36 seats when presidents are below that mark.

The clear implication is that the Democrats are vulnerable to losing a significant number of House seats this fall with Barack Obama’s approval rating averaging 45% during the last two full weeks of Gallup Daily tracking. The Republicans would need to gain 40 House seats to retake majority control.

On a historical basis, the Democrats under Jimmy Carter suffered the slimmest seat loss of a party whose president was below 50% approval, losing 11 seats in the 1978 midterms. More recently, Bill Clinton in 1994 and George W. Bush in 2006 saw their parties lose enough seats in the House to turn party control over to the opposition party when they had less than majority approval.

Assuming that Barack Obama retains his current Gallup approval rate of 45%, what kind of losses can Democrats expect in November?  Bill Clinton lost 53 seats in the House with a 46% rating in 1994, and LBJ lost 47 seats with a 44% rating in 1966.  Anything above 39 seats gives control of the House back to the Republicans.

Carter’s limited loss was an anomaly anyway.  It followed on the heels of Watergate, when voters were still angry enough at Republicans for Richard Nixon that any large-scale gains were out of the question.  That’s why Gerald Ford lost 47 seats despite having a 54% approval rating three months after becoming President in 1974.

This year seems different from most of those mentioned, for one big reason: the economy.  In 1994, Bill Clinton lost big because of his nanny-state overreach, and that was when the economy was actually adding jobs and growing steadily.  This year, not only has Obama spent the entire year attempting to expand government to unprecedented levels, he’s also spent the economy into stagnation at the same time.  Carter had Watergate to protect him, but Obama has nothing except the tiresome demonization of George W. Bush.