WASHINGTON (AP) - The Senate is preparing to begin debating new gun control measures, and some of President Barack Obama's fellow Democrats are poised to frustrate his efforts to enact the most sweeping limits on weapons in decades.

These Democrats from largely rural states with strong gun cultures view Obama's proposals warily and have not committed to supporting them.

The lawmakers' concerns could stand in the way of strong legislation before a single Republican gets a chance to vote "no."

All eyes are on a core group of these Democrats, including Sens. Max Baucus of Montana, Mark Begich of Alaska and Mark Pryor of Arkansas, who are up for re-election in 2014.

The Senate Judiciary Committee begins hearings Wednesday.

Education Secretary Arne Duncan is joining a rally for gun control today on the National Mall. So will residents from Newtown, Conn., along with parents, pastors and survivors of gun violence. The group One Million Moms for Gun Control, the Washington National Cathedral and two other churches are co-sponsoring the march.So will residents from Newtown, Conn., along with parents, pastors and survivors of gun violence. The group One Million Moms for Gun Control, the Washington National Cathedral and two other churches are co-sponsoring the march.