"The Mitchell Trio, whose last 'successful' album, Typical American Boys, featured at least 2/3 (or more) blatantly-leftist songs...."

I'm not sure how you're measuring success – I thought the later albums with John Denver were very good – but let's look at the tracks on Typical American Boys:

You Were On My Mind
Jesse James
Cherry Tree Carol
Which Hat Shall I Wear
The Last Thing On My Mind
The Natural Girl For Me
Waves On The Sea
One Man's Hands
Yowzah
My Name Is Morgan
Gorpus Morpus
With God On Our Side

That's 12 tracks. Two-thirds of 12 is eight – can we find eight (or more) "blatantly leftist songs" here?

Certainly we can count Which Hat Shall I Wear, One Man's Hands, Yowzah, and With God On Our Side. That's four. I don't remember what Waves On The Sea is about, maybe it's blatantly leftist, that's five.

But I wouldn't classify You Were On My Mind as blatantly leftist, nor Jesse James, nor Cherry Tree Carol. There's nothing particularly leftist about The Last Thing On My Mind, or The Natural Girl For Me, or My Name Is Morgan. And Gorpus Morpus is an instrumental.

So I count at most five tracks out of 12 – less than half – as blatantly leftist.