Politico isn’t left-leaning, although I’m sure it seems that way to you (anything that isn’t extreme right-wing always looks left-leaning from that perspective). There are many on the left who regard Politico as right-leaning, for the same reason.
However, this story had a misleading headline, and that has nothing to do with ideology. It’s verifiable fact. Politico didn’t poll on the Trump Travel Ban itself. They polled on the modifications to it mandated by the Supreme Court — modifications that Trump is vigorously fighting.
And the difference between the ban Trump wants and the modifications ordered by the Supreme Court is a big difference. Making this headline very misleading. Especially as it’s being promoted by Spicer in all its wrongness and no doubt others on the right.