The answer is SEVEN:

1. One to deny that a lightbulb needs to be replaced.
2. One to attack and question the patriotism of anyone who asks questions about the lightbulb.
3. One to blame the previous administration for the need of a new lightbulb.
4. One to arrange the invasion of a country rumored to have a secret stockpile of lightbulbs.
5. One to get together with Vice President Cheney and award a one million dollar no-bid contract to Halliburton Industries for supplying a lightbulb.
6. One to arrange a photo-op session showing Dubya changing the lightbulb while dressed in a flight suit and wrapped in an American flag.
7. And finally one to explain to Dubya the difference between screwing a lightbulb and screwing the country.

Source: monochrom bagasch