World leaders are calling her privately to ask if they can endorse her presidential campaign in hopes of stopping Donald Trump, former Secretary of State Hillary Clinton said Sunday.A Trump presidency would hurt America's standing in the world, Clinton argued."I am already receiving messages from leaders, and I am having foreign leaders ask if they can endorse me to stop Donald Trump," Clinton said during a CNN Democratic forum. "And I am like, 'No, this is up to Americans, thank you very much."When asked by forum moderator Jake Tapper if she'd liked to identify any of the leaders who have endorsed her, Clinton declined.She did say, however, that some had backed her publicly, including Italian Prime Minister Matteo Renzi.Renzi said he was making wishes known as a private citizen and as head of Italy's center-left party.