Or is it only okay if the President is Republican?

Dems already did it. https://www.foreign.senate.gov/imo/media/doc/5-4-18%20Menendez%20joint%20letter%20to%20General%20Prosecutor%20of%20Ukraine%20on%20Mueller%20investigation.pdf

That looks like a letter asking the Ukraine to cooperate with a legitimate American investigation, which is a far different thing.

Threatening to cut off aid to get dirt on a political opponent is exactly what is in the letter. In both cases investigations are underway, and we only have Muller's probe being used as leverage in elections. Thus your attempt at a distinction has not difference.

So by this logic only thing anyone has to do to get out of corruption charges is announce his or her candidacy for the next presidential election, and suddenly they are 100% untouchable, good to know.

@ViktorSamoja - not sure what you mean. Of course you if you do something corrupt you are subject to corruption charges. This is once again a lot different than asking a foreign government to dig up something on you.

If you have justified suspicions of foul play should you just let it go? All Trump asked is can they check if there was foul play involved, he did not threaten or insinuate anything, you people are really stretching the whole concept of digging up dirt on the opposition, especially considering the race has not even properly started yet, we don't even know if Biden can get the nominee.

There are legitimate ways for the law enforcement to investigate someone and to cooperate with other countries, but this isn't it.

It's rather hard for a law enforcement in US to investigate something in another country, that's why you have a president to preside over such matters.

No, law enforcement co-operation between countries is not uncommon. If there were problems and the president after that put pressure on them to cooperate that would be seen as doing the legitimate business of the US.

Which is exactly what he did.

No, he did not. There was no legitimate US law enforcement investigation cooperating with the Ukraine that Trump pressured them to cooperate with.

Now you are just splitting hairs.

Not at all, I'm just pointing out that there is a legitimate way to go about things and an illegitimate way to go about things.

I very much disagree. If Obama had done such a thing he would have been impeached in short order.

Look, i am not a lawyer, but i know a witch hunt when i see one, had Obama did this it would not be such a big deal, but Democrats just want a justification to remove Trump, whatever that may be, the idea for impeachment had been floated since before Trump was even sworn in, and ever since then the democrats have been jumping on every chance they had, no matter how minor, to force it trough.