Oregon wasn’t / isn’t as far left as people think. It was legit swing state in the Bush 43 elections. Clinton got higher margins because he was really popular, and there was Perot.
Obama in 2008 pulled away in that big 2008 year, and he maintained his coalition in 2012. Hillary saw the vote totals go back to normal for the Dems, but it seems Trump wasn’t a good fit for the state (got less votes than Romney did here).
If the Republicans could ever pull off a solid 4-5% nationwide win (which they haven’t done since 1988), then Oregon is a state that will surely go for them. This state isn’t like Massachusetts, New York, or Washington D.C.
Republicans need at least a 7-8 point win nationally to win Oregon and even then it would basically be to them what Indiana was to Obama in 2008