Four more Democrats, including two incoming senators from Republican-leaning states, have pronounced themselves open to new gun laws. 

In a statement, North Dakota Sen.-elect Heidi Heitkamp said that "possible changes to our gun laws" would be part of the conversation after the elementary school shooting in Newtown, Conn. "As always, I will listen closely to North Dakotans and seek their input on any possible changes to current law," she said. 

Indiana Rep. Joe Donnelly, who will replace retiring Republican Sen. Dick Lugar in January, told CNN Monday night, "I think there's a discussion beginning. I heard [West Virginia] Senator [Joe] Manchin this morning, and I think everybody's willing to listen and be part of that discussion."

Heitkamp got an 'A' from the National Rifle Association in her race against Rep. Rick Berg (R). Donnelly got the NRA's endorsement in past House races.

Rep. Martin Heinrich, the Democratic senator-elect from New Mexico, told a local paper Monday, “I don’t need a 25-round clip for effective home defense, and I sure don’t need one for hunting. That’s just too much killing power. It defies common sense.” The congressman has gotten 'A' Ratings from the NRA in the past. 

South Dakota Sen. Tim Johnson, another NRA-backed Democrat, said in a statement that the "tragedy will certainly force us as a country to have a discussion about our gun laws, as well as our mental health system." Sen. Bob Casey did not mention guns in his response but said that "everything should be on the table."

Manchin said Monday morning that the Newtown massacre made clear the need to consider new regulations on assault weapons. Virginia Sen. Mark Warner and Senate Majority Leader Harry Reid (D-Nev.), both strong supporters of gun rights, joined him in calling for action.