Vice presidential candidates Dan Quayle and Lloyd Bentsen counted down the hours to Wednesday night's nationally broadcast debate as the two presidential contenders vowed to help America's forgotten class.

Republican Quayle promised to focus his attack on Democratic presidential nominee Michael Dukakis, not his debate opponent Bentsen, when the two running mates clash at the Civic Auditorium in Omaha, Neb."Dukakis is running for president, and he's the one I'm very concerned about becoming president. It would be a very troubling notion for many Americans," Quayle told reporters Tuesday on his campaign plane from Washington, D.C.

Bentsen is hoping to counter what he believes are distortions of Dukakis' record, especially the Democratic presidential nominee's stand on defense and crime.

"Tomorrow night we're going to have 90 minutes to present Mike Dukakis' vision of America _ an America on the move, an America that believes in excellence in education for all of our children," the Texas senator told a flag-waving crowd of more than 500 people at the Omaha airport.

Bentsen's running mate _ the Massachusetts governor _ was limiting his campaign appearances tending to gubernatorial duties in Boston and later attending a debate-watching party.

George Bush was speaking to high school students in Littleton, Colo., before addressing rallies in Denver and Oklahoma City.

The presidential candidates will meet in their second debate next week in Los Angeles, but apparently they won't confront each other on ABC-TV's "Nightline" _ in an open format outside the other two debates' tight restrictions.

Dukakis accepted the network's invitation, with spokesman Dayton Duncan saying, "We thought it was a great opportunity for the American people to get beyond the slogans and balloons and bring George Bush out from behind the flag and get him to talk about the issues."