NEW YORK – A presidential debate dubbed by organizers as the “first in the nation” is also the first to get the brushoff by top candidates.

Both former New York Mayor Rudy Giuliani and Arizona Sen. John McCain – the leading Republican contenders for the White House in 2008 – will skip an April 4 debate planned in New Hampshire, officials said.

The debate – to be hosted by CNN and New Hampshire’s WMUR-TV and broadcast nationally – is part of the cable network’s “first in the nation” debate series, with Republican presidential hopefuls scheduled for April 4 and the Democrats on April 5.

McCain is expected to be in the Middle East on April 4 and Giuliani has an unspecified scheduling conflict, sources said. The two top GOP hopefuls have both said yes, however, to a May 3 debate planned at the Ronald Reagan Presidential Library in California.