With conservatives (aka "the base") abandoning the President in droves -- witness Peggy Noonan this morning -- and with the President himself saying those who oppose the bill "don't want to do what is right for America," the next set of polling numbers may be gruesome for the President. (Some have observed that the bad news on the economy will affect the numbers as well, but at 28%-34% percent, it has to be the 'true' believers that are still in support of the President.)
On a historic basis, Nixon's low water mark was 24% (early in 1974), and Carter's was 28% (summer of 1979). The lowest modern rating was Truman's 22% in early 1952.
The prediction here: Bush will bottom out below 20%.