From the Associated Press:

A big crowd is expected in Concord, N.H., when the House Judiciary Committee considers two bills that would repeal New Hampshire's same-sex marriage law.

... Democratic Gov. John Lynch has said he will veto a repeal bill if it reaches his desk. Republicans hold supermajorities in both the House and Senate which would be enough to override a veto if the GOP caucus was united in repealing gay marriage.

The law has been in effect a little over a year. [source]