My choice: President James Marshall (Airforce One)

Rationale: Following the siege of Airforce One by Kazahkstani terrorists, and the subsequent liberation of the craft and the hostages by Marshall himself, Marshall's approval rating would likely improve at an unprecedented rate and likely run with little real competition in the next election. This would also allow his presidency to make more moves politically, passing more legislation that would enshrine his more militant interventionist policies in law and also give him more power and influence as president. But, in order to maintain his high approval ratings and to appease the opposition in government, significant reforms are also passed which take affirmative action on key issues like health care, education, gun control, etc.

What could turn his presidency into a autocracy is the effects his policies have on international affairs. I would imagine a president like Marshall would end up stoking a lot of fires overseas, possibly even in countries which had historically been allies to the U.S., and the perceived increased threat against national security would be a springboard to push for repealing Article 22 and allowing Marshall to run for and win successive terms as well as instituting constitutional ammendments making the president's power absolute.