Conversation so far:
Who was the Republican nominee relative to Ron Paul?
Ron Paul said that under no circumstances would he be endorsing either of the two main parties' candidates (John McCain – Republican Party, or Barack Obama – Democratic Party).
What did Ron Paul refuse?
Ron Paul said that under no circumstances would he be endorsing either of the two main parties' candidates (John McCain – Republican Party, or Barack Obama – Democratic Party).
What was Ron Paul's reasoning for saying that under no circumstances would he be endorsing either of the two main parties' candidates in the 2008 presidential campaign?
Ron Paul said that under no circumstances would he be endorsing either of the two main parties' candidates because there were no real differences between them.

Question: What time period was this?
Self-contained rewrite: What time period was Ron Paul saying that under no circumstances would he be endorsing either of the two main parties' candidates?