Too much generalization on this thread.
For starters, Congressional Democrats are not "the left," and they weren't in 2003 or for Libya. They're mostly expedient corporate politicians who are afraid of not "looking tough."
The anti-war left is one of the most principled sub-groups in American politics. Every anti-war lefty I know personally has been anti-war and anti-conflict their whole life, whether a Republican or Democrat was President. I always say that I have been against every single war except Afghanistan, and I regret my support for that one. I have a friend w/ a bumper sticker that says "I'm even against the next war." Hillary lost the election in large part because anti-war lefties couldn't stomach her Iraq vote.
But let's also not impugn the current crop of Congressional Democrats without any foundation. Because they want Russia investigated, they're now war mongers who are yearning for Cold War II? Give me a flippin' break. Let me know when some of them start calling for invasion or war.
And last, this one goes out to anyone who supported the invasion of Iraq and criticized the left in 2003 for their opposition: shut up. You have not a single leg to stand on when it comes to this topic. You are a hypocrite and partisan, and your support of conflict shifts w/ the political winds & depending on who is in power. Beyond that, the Iraq War is one you do not get a mulligan on. It was an historically epic blunder, and the left warned you about the consequences. We were right, you were wrong. You should permanently recuse yourself from any discussion on foreign policy.