It is no secret that the proposed merger between Ticketmaster and Live Nation has sparked a lot of debate, but over the past few years, no single antitrust issue has led to the amount of opposition from members of Congress this one has, according to one of the deal’s critics.

Earlier this week, U.S. Rep. Bill Pascrell, Jr. of New Jersey sent a letter containing the signatures of 50 House members to Assistant Attorney General Christine Varney, head of the Department of Justice Antitrust Division, calling on her and the department to oppose the merger.

The amount of Congressional signatures is more than twice the number received on the next closest issue, the merger of satellite radio companies XM and Sirius, which eventually was allowed to take place.

One might have to look back to the Microsoft battle with the Department of Justice (DOJ) in the ’90s to see as much direct Congressional interest in an antitrust matter. During the eight years under President George W. Bush, DOJ officials were not as aggressive in reviewing antitrust matters. The issue led the New York Times to do a recent front-page story about how some Democratic leaders and members of the Obama administration have become uneasy over the department’s newfound strength, which could lead to political trouble for some Democrats who have worked hard to forge relationships with business leaders. If the DOJ gains a reputation for being tough on mergers, it could send a chill through the business community.

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Which makes the number of bipartisan signatures Pascrell was able to garner all the more impressive. Ticketmaster, Live Nation and DOJ officials did not return messages seeking comment this week.

“It’s truly remarkable,” said Washington, DC-based attorney David Balto, who testified before Congress against the merger. When the XM-Sirius deal was debated, the National Association of Broadcasters spent close to $3 million to fight the merger, but failed, and Balto estimates a similar letter of opposition from Congressional members opposed to that deal received fewer than 20 signatures. “This shows the profound level of concerns over the antitrust effects of the Ticketmaster-Live Nation merger. To get 50 signatures is stunning, almost unprecedented.”

Pascrell’s office said that there is a chance that more members of Congress might sign on, even though they are not actively seeking them. Also this week, Sen. Herb Kohl, who chaired a Senate subcommittee hearing reviewing the deal, also came out against the merger.

“We’ve been more focused on the end goal of urging the Justice Department to fight this merger than on the man-on-the-moon aspect of the importance of the number of signatures,” Paul Brubaker, communications director for Rep. Pascrell, told TicketNews. “But having said that, it is a big deal. Right now, what’s on the minds of members of Congress is the health care debate, so to cut through the din of that measure is impressive.”