Bitcoin slid to a two-month low on Thursday, extending a month-long fall, as uncertainty over U.S. presidential elections and reports of bitcoin supply from a defunct Tokyo-based crypto exchange weighed. Bitcoin fell more than 2% to $57,843, its lowest since May 2, and has lost more than 6% so far this week. The world's biggest cryptocurrency has been under pressure in recent months, its slide accelerating this week after the first debate between U.S. presidential candidates Joe Biden and Donald Trump raised the spectre of Biden being replaced as a candidate.