Mitch McConnell might filibuster gun legislation. (Bloomberg)

Senate Minority Leader Mitch McConnell (R-Ky.) plans to join a Republican filibuster of legislation aimed at curbing gun violence should Senate Majority Leader Harry Reid (D-Nev.) bring it to the floor.

"While nobody knows yet what Senator Reid's plan is for the gun bill, if he chooses to file cloture on the motion to proceed to the Reid Bill (S. 649), Senator McConnell will oppose cloture on proceeding to that bill," a McConnell spokesman said. 

Reid said Monday that the Senate would move this week on the legislation, which includes an expanded background check program for gun sales, new federal funding for school security programs and would make gun trafficking a federal crime.

McConnell aides wouldn't say whether he would support a modified version of the bill that includes new language negotiated by moderate senators working on a potential compromise.

The Kentucky senator joins 13 Senate Republicans who are threatening to filibuster the legislation because they believe the proposals would infringe on the Second Amendment.

Reid criticized those Republicans Monday, saying "every one of these measures deserves a vote, a yes or no."