Republican presidential candidates steered clear on Thursday of addressing the role gun rights and racial tensions may have played in a deadly mass shooting in South Carolina as Democratic candidate Hillary Rodham Clinton called for the United States to face what she called the "hard truths" underpinning the tragedy.

The responses to the attack in Charleston, in which a white man is suspected of killing nine black people at a historic church, showed the contrasting pressures facing White House hopefuls in each party as they prepare for primary contests.

Clinton and other Democrats are appealing to a racially diverse voter base that has been frustrated by an inability to tighten gun laws after other mass shootings. Those voters are also increasingly vocal about heavy-handed law-enforcement tactics in black communities following a series of police killings of unarmed African-American men.