None, Ryan will win easily.
It may carry a little weight for Ryan that The Donald has given at least lukewarm support.
Ryan did not need Trump's "endorsement". Trump did that for other reasons including the fact that he knew Ryan would win anyway. Trump wants a chance to win Wisconsin and he can't even begin to work towards that without the Ryan, Walker, etc, GOTV machine working with him rather than against him.
You’re right. Ryan is ahead by something like 50 points. Will win in a walk. The idea that he is “running scared” is a bit of fantasy unfortunately.
He is an open-borders traitor against the USA, but his district appears to like him.