Washington, Nov. 4 : Having already secured New Hampshire, Democratic presidential candidate Barack Obama, continues to maintain a clear advantage over Republican rival John McCain, even as both made final appeals in battleground states in advance of Tuesday''s balloting.

The Washington Post-ABC News tracking poll showed Obama leading by nine percentage points -- 53 percent to 44 percent. That is slightly narrower than the 11-point lead Obama held the day before, but in general, Obama''s lead has held steady for the past several weeks.

State and national polls underscored the steep hill McCain has to climb in the final hours to reach the 270 electoral votes needed to win the White House.

Burdened by President Bush''s unpopularity and an economic crisis that redrew the race in September in Obama''s favor, the Arizona senator sprinted through a series of critical states yesterday -- all but one of which President Bush carried four years ago -- exhorting his supporters to help him defy the odds.

The Washington Post said that Obama concentrated on Florida, North Carolina and Virginia, appealing to supporters to produce a huge turnout in those battlegrounds as he sought to checkmate McCain by keeping alive as many options as possible for winning an electoral college majority.

The strategy, laid down in the summer at the beginning of the general election, has proved successful in the late stages of the race and will require McCain to win virtually every state where the polls are close to deny Obama a victory.

Obama, the first African American nominated by a major party, is looking not only to win the presidency but also to produce a popular vote majority, which no Democrat has done since Jimmy Carter in 1976.

Carter won just 50.1 percent of the vote that year. By invading Republican territory in the South, Midwest and Rocky Mountains, Obama also is bidding to redraw an electoral map that has been static and closely divided into red and blue states in the past two elections.

According to the Washington Post, if Obama were to win, he probably would enter the White House with enhanced Democratic majorities on Capitol Hill.

House Democrats are looking at the potential for a gain that could come close to equaling the 31 seats they added two years ago when they took control of both chambers. Senate Democrats are trying to add substantially to the 51 seats they currently control, with reaching 60 not out of the question.

Almost 20 percent of those surveyed said they had already voted, testament to the long lines seen in a number of states at early balloting sites, and 90 percent said they are following the race closely -- 63 percent said very closely.

The economy dominates the national agenda, with half citing it as the top issue, far eclipsing all other issues, including the war in Iraq.

The electorate views both candidates favorably. More than three in five (63 percent) said they have a favorable impression of Obama, while just over half (54 percent) said they have a positive view of McCain.

Some other national polls also showed a small tightening in the margin between Obama and McCain. Obama''s lead varies from 5 points to 11 points in about a dozen national polls released yesterday.

But in almost every case, the Democratic nominee had a clear lead and at least 50 percent support, with a small percentage of the electorate undecided.

That means McCain not only has to win virtually all the undecided voters but also peel away some voters who currently say they support Obama.

Obama is now looking at the prospect of winning by a potentially large margin in electoral votes, although the estimates by various analysts vary wildly.

A weekend analysis by The Post estimated that Obama is well ahead or narrowly leading in states that add up to 291 electoral votes. Other states, totaling 87 electoral votes, were too close to call. (ANI)