Oct. 26 (Bloomberg) -- Democrat Barack Obama widened his lead over Republican John McCain in most national polls and surveys of battleground states as the Nov. 4 American election approaches.

The Illinois senator was up 8 points over presidential rival McCain in an average of polls released during the last week, according to RealClearPolitics.com. The previous week, Obama was up about 6 points.

Obama also has built leads in so-called battleground states including Pennsylvania and Ohio and he has an edge over McCain in some states that were Republican strongholds, such as Virginia and North Carolina.

``He had a great week,'' said Peter Brown, assistant director of the Quinnipiac University Polling Institute in Hamden, Connecticut. Speaking of McCain, he said, ``No one has come from this far back in this little time.''

The Gallup daily tracking poll shows Obama up 5 points, nationally, a lead he's maintained throughout the past week. The CBS/New York Times and ABC/Washington Post polls put Obama up 13 points and 9 points respectively, while the latest Newsweek poll shows Obama leading McCain by 12 points.

Rasmussen Reports and Reuters/C-SPAN/Zogby tracking polls released today have Obama ahead by 8 points and 5 points respectively. While Rasmussen shows Obama's support has stayed between 50 and 52 percent for the last 31 days, the Reuters poll shows his lead has dropped from a high of 12 points Oct. 23.

North Carolina

In North Carolina, which has voted for the Republican candidate in nine of the last 10 elections, Obama and McCain are in a dead heat. A poll by Rasmussen Reports has McCain ahead by 2 percentage points and another by Charlotte television station WSOC has Obama in front by the same margin. In Virginia, four recent polls put Obama in the lead, by an average margin of 7 points.

In Colorado, which went to Republican President George W. Bush in 2004, Obama has taken a 12-point lead over McCain, according to a Rocky Mountain News/CBS4 News poll released late yesterday. The RealClearPolitics.com average of four Colorado polls shows Obama ahead by 7 points.

Obama and McCain, an Arizona senator, are campaigning this weekend in Colorado and the swing state of New Mexico. Obama also made appearances in Nevada. All three states were won by Bush in 2004 and Obama has targeted them to flip to his column this year.

Obama has consolidated support in the upper Midwest states of Minnesota, Wisconsin and Michigan that have reliably voted for Democratic presidential candidates, while tying McCain in Indiana, a state that hasn't favored a Democrat since 1964.

McCain's Map

Because of Obama's strength in states won by Bush in 2004, McCain now must focus on a limited number of contests for a victory, said Whit Ayres, a Republican pollster based in Virginia. ``It just makes it more challenging,'' he said, comparing it to trying to draw an inside straight in poker.

``Pennsylvania is critical,'' said Ayres, ``You've got to hold Ohio and Florida.''

Bush won Ohio and Florida in 2004, while Pennsylvania went to Democrat John Kerry, a senator from Massachusetts. Together, the three states have 68 of the 270 Electoral College votes needed to win the presidency.

Obama leads by 11 points in Pennsylvania, 6 points in Ohio and 2 in Florida, according to the Realclearpolitics.com average of polls in those states.

A Boston Globe poll released today shows Obama with a 15- point lead over McCain in New Hampshire, where McCain campaigned last week and where he won the Republican primary this year and in 2000. The state went for Bush in 2000 and Democratic candidate Kerry in 2004.

To contact the reporter on this story: Christopher Stern in Washington at cstern3@bloomberg.net

Last Updated: October 26, 2008 16:01 EDT