After buzz this morning that Mort Zuckerman was seriously mulling a run for the Senate, the Washington Post says tonight that the New York Daily News owner is now leaning against a run. Sources close to Zuckerman told the Post that there are three key considerations holding him back: his two young children, the recent death of longtime business partner Ed Linde, and his reluctance to give up associations with not-for-profit groups (most notably, his support for pro-Israel groups and groups working toward Mideast peace). Despite these concerns, the Post says Zuckerman — who is currently the most viable Republican challenger to take on Democrat incumbent Kirsten Gillibrand — “remains intrigued by the idea” and is still “very much making up his mind.” [Fix/WP via Ben Smith/Politico]

Update: Zuckerman has officially announced he will not join the Senate race. "At this time, it is very difficult to see how I can devote the necessary time to either a campaign, or to working in Washington, if I were to win," he told the Daily News. [NYDN]