The emoluments clause actually covers this very issue. You are not allowed to accept a thing of value from another country. I know it seems a little redundant but I guess we have to put it in large bold print for people who do not follow the Constitution. You cannot accept anything of value from another country that would help you in an election. The issue is that there is a fear that another country would expect some form of repayment for their help. We just had the President of the United States clearly say he would listen to opposition information from another country. That is a gift you cannot accept. We need to impeach him.