WASHINGTON, March 29 (Reuters) - U.S. Republican Senator Rand Paul on Wednesday blocked a bid to fast-track a ban of popular Chinese-owned social media app TikTok, which more than 150 million Americans use, citing concerns about free speech and uneven treatment of social media companies. "I think we should beware of those who use fear to coax Americans to relinquish our liberties," Paul said on the Senate floor. "Every accusation of data gathering that has been attributed to TikTok could also be attributed to domestic big tech companies." Republican Senator Josh Hawley had sought unanimous consent for a TikTok ban...