The Senate voted 68 to 31 to proceed to debate on legislation to curb gun violence, beginning what observers expect to be weeks of argument on the most consequential congressional action on firearm regulations since the 1990s.

Sixteen Republicans joined 52 Democrats to approve a motion to proceed. Two Democrats joined 29 Republicans in opposing the motion.

"The hard work starts now," Senate Majority Leader Harry M. Reid (D-Nev.) said after the vote, noting that the Senate now faces potentially weeks of debate on the issue.

"There are powerful feelings about each of these proposals — both strong support and strong opposition," Reid said. "But whichever side you are on, we ought to be able to agree to engage in a thoughtful debate about these measures."