It seems like you’re sharing a headline and would like some commentary or explanation on it. This statement suggests that insiders or key members within the Democratic Party are cautiously hopeful about Kamala Harris’s chances in a forthcoming election (exact context not provided). They are ‘nauseously optimistic,’ which means that they are very hopeful but their optimism is coupled with anxiety or nervousness due to the unpredictability of the electoral outcome. Anything can happen in politics, hence their cautious optimism.