President Barack Obama dropped below 50 percent in his job approval rating in another poll Friday -- a politically dangerous trend that could spell major trouble in next year’s elections if it’s not reversed.

The Gallup Poll found 49 percent of Americans approving of the way Obama is doing his job, calling it the 4th fastest drop to the sub-50 mark in more than half a century.

It follows polls by Quinnipiac University and Fox News earlier this week that also found Obama dropping below majority approval for the first time.

“Of the post-World War II presidents, Obama now is the fourth fastest to drop below the majority approval level, doing so in his 10th month on the job,” Gallup says in its analysis.

“Gerald Ford dropped below 50% approval during his third month in office, and Bill Clinton did so in his fourth month. Ronald Reagan, like Obama, also dropped below 50% in his 10th month in office, though Reagan's drop occurred a few days sooner in that month (Nov. 13-16, 1981) than did Obama's (Nov. 17-19, 2009).

“But all presidents except John Kennedy dropped below the majority approval level at some point in their presidencies, and all recovered after the first time below this mark to go back above 50% approval.”

Obama’s fellow Democrats know that it’s critical for them that he rebound.

As Republican pollster Bill McInturff notes, a president’s approval rating is a very important measure of his party will do in the mid-term Congressional elections like thos coming up in 2010.

Since the mid-term election 1962, presidents with approval ratings above 60 percent have gained an average of 1 seat in the House of Representatives.

Those with approval ratings in the 50s have lost an average of 12 seats.

And those with an approval rating below 50 percent – Johnson in 1966, Ford in 1974, Reagan in 1982, Clinton in 1994 and Bush in 2006 – have lost an average of 41 seats.

With a 258-177 margin now in the House, a 41-seat swing is exactly the number it would take for the Democrats to lose control.