U.S. presidential hopefuls - both Democrats and Republicans - are sparring among themselves on issues such as the economy, tax cuts and race as they prepare for upcoming primary elections.

Supporters cheer as Democratic presidential hopeful Sen. Hillary Rodham Clinton takes the stage in Manchester, New Hampshire, 8 Jan. 2008

Senator Hillary Clinton of New York said in a television interview Sunday that supporters of her Democratic rival, Senator Barack Obama of Illinois, are "deliberately distorting" a comment she made about civil rights last week.

Recalling the late Martin Luther King's campaign for racial equality during the 1960s, Clinton said that dream was realized when former President Lyndon Johnson won passage of landmark civil-rights legislation. Clinton said, "It took a president to get it done" - which some interpreted as giving more credit for leadership on civil-rights issues to Johnson than to King.

Democratic Presidential hopeful, Senator Barack Obama, speaks at a rally at Dartmouth College in Hanover, New Hampshire, 8 Jan. 2008

Obama, who hopes to become the United States' first black president, said Clinton's remark was unfortunate and ill-advised, but he added it would be "ludicrous" to think that his campaign organization did anything to publicize her comments.

In another television appearance Sunday, former North Carolina Senator John Edwards spoke about Americans' need for a universal health-care system, and for measures to stimulate a declining economy and sustain the nation's middle class.

In an interview with Fox News, Former New York City Mayor Rudy Giuliani talked about his tax proposals. Asked about his relatively weak showing in the first two electoral tests for Republican presidential challengers - the Iowa caucus and the New Hampshire primary weak position, Giuliani said he is focusing his efforts on a primary election later this month in Florida.

Michigan's Republican primary on Tuesday this week could have a major impact on former Massachusetts Governor Mitt Romney's candidacy, which has faltered in the Iowa caucus and New Hampshire primary earlier this month. Romney's late father was a governor of Michigan, but public-opinion polls indicate a surge in favor of Senator John McCain of Arizona. Former Arkansas Governor Mike Huckabee, the Republican winner in Iowa, also is campaigning hard in Michigan.

South Carolina's Democratic primary is on Saturday and the southern state's Republican primary will follow one week later. Nevada's Democratic caucus, also on January 19, will be closely watched, as the first contest for Clinton, Obama and Edwards in a state that has a substantial number of Hispanic voters.

Some information for this report was provided by AFP and Reuters.