Why do you think Republicans would institute an export ban? Trump has been touting every export deal he can (especially promises to purchase petroleum), he has even been measuring import/export levels as if foreign countries are cheating the U.S. if they export more to the U.S. than they import from it.

I am not confident that the Democrats would even implement such a ban, as they get pretty big campaign donations from the oil industry as well.

It also wouldn't work. The US has refineries which can only run on various foreign import grades of oil.

The US produces oil which goes to foreign refineries for the same reason.

The effect of "banning exports" is non obvious.

Conversely not starting a war with Iran had some really obvious benefits that every previous administration recognized.