I think both of these things are true, actually. It does seem that some on the left are fine with war as long as it's a Democrat doing it. For example, look at

I think both of these things are true, actually. It does seem that some on the left are fine with war as long as it's a Democrat doing it. For example, look at Hillary Clinton's complicity during the Honduran coup, and how little criticism she received for it. Or deportation and drone strikes under Obama, as another example. However, it's also true that the anti-war movement died off partly due to failure essentially, as the Iraq War proceeded with essentially no resistance from elected officials, and no coverage from the mainstream media. I think this, more than partisanship, explains why it's basically dead in the water now. If the movement fails to achieve its goals, people will eventually go home. This all happened within W's term. Protest altogether didn't die out under Obama, however, Occupy Wall Street started in 2011, and was heavily critical of Obama's coziness with the finance industry. Within left movements that exist now, many seem to see a through-line from Occupy Wall Street. Overall, this speaks to the narrative about tribalism, because there's a tendency to see the opposing group as one mass, when in reality, there are different groups within each side that may disagree with each other as much as they do the nominally-opposed groups. This tendency is also exacerbated by the two-party system in the US that smushes what would really be 3-6 parties together into two.