There was more friendliness than fireworks the first few times Democratic candidates for president shared the same debate stage. That changed Sunday when former Secretary of State Hillary Clinton and Vermont Sen. Bernie Sanders fought bitterly over some of the party's hallmark policies: health care, bank regulation and gun control.

The escalating fight comes as polls show a tightening race between the two in the early-voting states of Iowa and New Hampshire. And both tried to make the most of their last nationally televised debate before Iowa voters head to the polls in two weeks.

From a stage just a stone’s throw from the Charleston, S.C., church where nine black worshippers were gunned down, Clinton blasted Sanders for a vote that protected gun manufacturers from lawsuits when their weapons were used in a crime. Sanders urged Democrats to look at an overall record on restricting gun rights that he said made him no friends at the National Rifle Association.