US President Barack Obama has accused Republicans of stooping to political stunts in an effort to block gun reform.

In a speech delivered in Hartford, Connecticut, not far from Sandy Hook Elementary School, where 20 children and six adults were shot dead in December, he contrasted the courage of parents whose children were killed with US lawmakers who he said feared the wrath of the powerful American gun lobby.

His efforts to introduce a ban on assault weapons and a limit on high capacity magazines appear unlikely to pass Congress.

There's also doubts over the prospects of expanded background checks for gun owners being introduced.

The President says the victims' families deserve the chance to vote on new firearms controls: