On the morning of June 10, 1964, Senator Robert Byrd (D-W.Va.) completed a filibustering address that he had begun 14 hours and 13 minutes earlier opposing the legislation. Until then, the measure had occupied the Senate for 60 working days, including six Saturdays. A day earlier, Democratic Whip Hubert Humphrey of Minnesota, the bill's manager, concluded he had the 67 votes required at that time to end the debate and end the filibuster. With six wavering senators providing a four-vote victory margin, the final tally stood at 71 to 29. Never in history had the Senate been able to muster enough votes to cut off a filibuster on a civil rights bill. And only once in the 37 years since 1927 had it agreed to cloture for any measure.