Minnesota's U.S. Senators Amy Klobuchar and Al Franken joined more than 20 of their  Democratic colleagues Wednesday in demanding that people on terrorist watch lists be banned from buying guns and that background checks be required in weapons purchases at gun shows, online sales and in other commercial transactions.

The Democrats took over the Senate floor at 11:21 Wednesday morning to filibuster for legislation that they said could keep firearms out of the hands of terrorists and criminals. They still held the floor six hours later when Klobuchar wrapped up a speech that supported the watch list gun ban and expanded background checks, as well as restrictions on firearms sales to those convicted of domestic abuse and stalking.

The filibuster came in reaction to what Klobuchar described as the "massacre" of 49 people at an Orlando night club Saturday. It delayed action on a bill that included funding for the U.S. Justice Department. Participants called for better ways to keep potential terrorists and criminals from acquiring firearms.

Klobuchar called the inability to keep guns out of the hands of known and suspected terrorists "a dangerous loophole."

Franken called attention to a new report from the Government Accountability Office. It showed that in the U.S., nine out of 10 people on terrorist watch lists who have tried to buy guns succeeded. Since 2004, those sales put 2,265 weapons in the hands of potential terrorists.

"If we are allowing over 90 percent of people on the terrorist watch list to purchase deadly weapons here at home," Franken said, "does that not suggest that we aren't coming close to doing everything in our power to combat terrorism and address gun violence?"