Never.
You want this changed? Figure out other energy sources. Nothing else will work.
The reason is that every individual has basically zero effect. So no one is motivated to make any changes.
> Everything else aside no President should be able to deny reality.
The President is irrelevant. He has very little on-the-ground effect. Maybe some media noise, which maybe might influence some. That's about it.
Either other energy sources are cheaper, or they are not. And that's about it.
A CO2 tax can't work unless it was implemented globally INCLUDING developing countries. (Which is a non-starter of course.) Because otherwise people will just ship industry and manufacturing elsewhere.
So there isn't much the president can do. I guess some subsidies, but there's a limit to how much of that you can do before they cause more harm than good.