I say it because the numbers dwindled before there were any "exit" dates. Even when he escalated in Afghanistan the numbers continued to fall. Even you, if you are honest, must notice that there are fewer protesters than before, and even less coverage of those few.You say it's because a liberal was elected but perhaps it was because that liberal actually put exit dates on the conflicts, or because the people who elected him appreciated losing the lone cowboy diplomacy and exaggerated rhetoric of the former prez.
Yes, I believe it is because of who is President. I believe that the vast majority of those who protested were protesting Bush with the war a convenient excuse to do so.
When it goes from many thousands gathering at the end of the Bush term, along with the anti-entourage each time he traveled to just a few so quickly it isn't because of future events that hadn't happened yet, it was because of the party of the person in the office.
As for Onceler, the numbers began to dwindle near the end of Bush's terms not because they aren't "indefatigable" but because they saw an end to what they were actually protesting. Bush's Presidency.