I would like to point out that while Bush himself did make such statements, many of the key figures in his cabinet made completely opposite statements.
10 of his cabinet members, including central ones such as Dick Cheney, Donald Rumsfeld, and Paul Wolfowitz, were signatories to the mission statement of a think-tank called The Project for a New American Century. This group had 25 signatories in total.
PNAC's stated goal was "to promote American global leadership." The organization stated that "American leadership is good both for America and for the world," and sought to build support for "a Reaganite policy of military strength and moral clarity."
Observers such as Irwin Stelzer and David Grondin have suggested that the PNAC played a key role in shaping the foreign policy of the Bush Administration, particularly in building support for the Iraq War.
Key PNAC members had been advocating regime change in Iraq since 1998.
One particular publication by PNAC which is discussed frequently is Rebuilding America's Defenses: Strategy, Forces and Resources For a New Century, published in September 2000. Here are some quotes from it which I consider signifigant:
The immediate task is to rebuild today's force, ensuring that it is
equal to the tasks before it: shaping the peacetime environment and
winning multiple, simultaneous theater wars; these forces must be
large enough to accomplish these tasks without running the “high” or
“unacceptable” risks it faces now.
None of the defense reviews of the past decade has weighed fully
the range of missions demanded by U.S. global leadership: defending
the homeland, fighting and winning multiple large-scale wars,
conducting constabulary missions which preserve the current peace,
and transforming the U.S. armed forces to exploit the “revolution
in military affairs.”
Further, the process of transformation, even if it brings
revolutionary change, is likely to be a long one, absent some
catastrophic and catalyzing event – like a new Pearl Harbor.
Emphasis mine. I do not mean to imply anything by the last quote. Being one of the more famous quotes from the document, however, I felt I had to include it.
I'd also like to point out that politicians do not always mean what they say, both during campaigns, elections, and their terms in office.
Whether or not Bush truly did agree with the sentiments of PNAC before 9/11, the fact that he selected so many of its signatories for his cabinet is, in my opinion, more of a political statement than anything he said during his campaign. Actions speak louder than words. To give Bush the benefit of the doubt, it's possible that he simply did not know his cabinet members very well. That would be grossly incompetent, which is certainly possible. I do not speculate on his personal character or motives.
Sources for claims about PNAC are in their own mission statement, and in the sources of the Wikipedia article on PNAC. Two sentences in this answer have been copied verbatim from Wikipedia.