Sen. Amy Klobuchar said she will continue to pursue federal legislation to improve consumer protections and transparency in ticket sales, even as the Justice Department filed a sweeping antitrust lawsuit against Ticketmaster and parent company Live Nation Entertainment on Thursday.

The lawsuit accuses them of running an illegal monopoly over live events in America — squelching competition and driving up prices for fans.

"They didn't go small ball," the senator said in an interview. "They had the Attorney General of the United States stand up and say, 'We need to break up the monopoly.'"

Klobuchar said she will continue to push her Fans First bill because the lawsuit will likely take a long time to work its way through the courts.

She said, however, that change could come soon because Live Nation is now on notice and that any actions can be considered in the lawsuit.

"They have to really watch their behavior," she said. "Hopefully, it will result in some changed behavior immediately and hopefully the end result is to break up the monopoly."

Klobuchar believes in a free market but said, "You can't have a free market if you have someone shutting out the competition."

She said the changes that result from the lawsuit will be good for music and sports fans.

"This is really about standing up against the big bully monopoly so consumers get better rates," she said. She likened it to consumers getting better rates on long-distance calls after the AT&T breakup.

Klobuchar noted that she and the late Sen. Orrin Hatch, R-Utah, first voiced concerns about the merger in 2009. Klobuchar also wrote a book about monopolies and serves as chairwoman of the Senate Judiciary Subcommittee on Competition Policy, Antitrust, and Consumer Rights.

The Associated Press contributed to this report.