Russia has become the slow burn of President Donald Trump's Administration. It is the issue that he and his team cannot get beyond.
They cannot get beyond it because they are skittish about accepting what is already known. They cannot get beyond it because they have not been as forthcoming as they could be about what they did. And they cannot get beyond it because they don't know what they don't know.
It's important to remember that much isn't yet known about the whole controversy, particularly the contacts between Trump campaign officials or advisers and the Russians. That there were contacts is not in dispute. Some appear routine, but the circumstances and the content of all those contacts is far from fully known.
The overarching issue is the attempt by a foreign government to disrupt a US election. Just as important is answering the question of whether there was any collusion or cooperation between the Trump campaign and the Russians in attempting to undermine Clinton's campaign.
Ambassadors routinely meet elected US officials. They are especially keen to learn as much as they can about someone who could become president and about the people around the candidate. Attorney-General Jeff Sessions' meeting with Russian Ambassador Sergey Kislyak last September easily falls into that category. Meetings between Kislyak and retired Lieutenant General Michael Flynn and White House senior adviser Jared Kushner could be seen in that way as well.