I’m trying to decide if this would be a net positive or negative.

Looking at the congressional districts for Oregon and Idaho it looks like about 5 or 6 districts that are all Republican controlled. Currently Idaho has two congressional districts that both lean heavily Republican. Shifting 5 or 6 Republican congressional seats from Oregon to Idaho I don’t see making a significant difference to Congress.

Looking at things in the Senate both Idaho senators are Republican and adding more Republican districts won’t really change that in any meaningful way. On the flip side both of Oregon’s Senators are currently Democrats and I can’t imagine removing a bunch of Republican voters from the state would do anything but reduce the chances of one of those Senate seats getting flipped.

I’m not really seeing any way in which this would help Republicans or hurt Democrats other than just by generally strengthening each party’s hold on its respective state.

It’s been a while since I’ve looked at this but not only is such an arrangement impossible without federal input (as the comment from tal states) but I seem to recall seeing that a lot of the counties looking to join the greater Idaho thing are some of the ones most dependent on the Oregon state government for funding. If they did manage to leave then it’d actually probably be a net boon for Oregon in terms of state resources going to places where people actually live.

The resultant Greater Idaho though? Suddenly saddled with a bunch of counties that need a lot of help to maintain services and seemingly a general political attitude of the government shouldn’t help people. In my personal opinion it’d turn pretty fucking distopian pretty quick, that is of course assuming that they could somehow get Oregon, Idaho and the federal government to agree to their scheme. I don’t think it’s going to happen, even if they can get some counties to sign off on it. But if they did the people of those same counties would likely come to regret it not long afterwards.

Also just as a brief note I think my information on this is like more than a year old and I don’t think I could find it again to to quote it. So if someone has better/more up to date info that negates anything I’ve said feel free to post it.