Howard Dean (search) is gaining ground as the leading candidate in the Democratic presidential contest but he appears to be a substantial underdog in a hypothetical matchup against President Bush, a national poll released Monday says.

The ABC News-Washington Post poll found Dean, a former governor of Vermont, backed by 31 percent of Democrats and those who lean Democratic. All other candidates were in the single digits.

Connecticut Sen. Joe Lieberman and Missouri Rep. Dick Gephardt were at 9 percent, Massachusetts Sen. John Kerry at 8 percent, retired Army Gen. Wesley Clark at 7 percent, North Carolina Sen. John Edwards at 6 percent, activist Al Sharpton at 5 percent, Ohio Rep. Dennis Kucinich at 2 percent and former Illinois Sen. Carol Moseley Braun with less than 1 percent. Fourteen percent were undecided.

When all respondents were asked who they would trust more with national security (search), 67 percent said Bush and 21 percent said Dean. When asked who they would trust more to handle domestic issues like Social Security (search), health care and education, they picked Bush by 50 percent to 39 percent.

In a head-to-head matchup, Bush led Dean by 55 percent to 37 percent. Few in the poll, including Democrats, knew a great deal about Dean and his positions.

According to state polls, Dean is battling for the lead with Gephardt and Kerry in Iowa and has a big lead in New Hampshire. He's showing increasing strength in other states as he picks up endorsements and attention. Al Gore (search), the 2000 Democratic presidential nominee, endorsed him Dec. 9.

As Dean has gained strength, Democratic insiders have grown more concerned that he would have a difficult time in a general election matchup against Bush. Aides counter that Dean's strength in motivating new voters and using the Internet as a tool will be valuable.

The ABC-Washington Post poll of 1,001 adults was taken Dec. 18-21 and has a margin of error of plus or minus 3 percentage points, larger for subgroups like Democrats.