Check the numbers
here - Bush was at 39% in mid-February, before Perot was really a factor. A month later, an ABC/WAPO
poll had Bush losing to both Clinton and Tsongas - again before Perot had really caught fire. He had a very mild rebound later in the spring, at the same time Clinton was struggling in the primaries, but that petered out after
the LA riots and some bad economic news (the June '92 unemployment rate increased to 7.8%). Perot's success was really a byproduct of Bush's unpopularity (and doubts about Clinton) rather than the driver of it.