A new public opinion poll shows Democrat Barack Obama leading Republican John McCain in the race for the White House by a margin of 47 to 41 percent.  The Wall Street Journal-NBC News poll was conducted as the general election campaign between Obama and McCain gets underway after months of primary and caucus votes to choose the major party nominees.  VOA National correspondent Jim Malone has a preview from Washington.

Either man would make history if elected.  Obama would become the first African-American president.  If McCain wins, he would be the oldest candidate elected to a first term in the White House.

Both men had their share of challenges in clinching their party nominations.

Obama was a newcomer to the national stage who was given little chance of defeating his heavily favored Democratic rival, Hillary Clinton.

Obama's insurgent campaign successfully portrayed the first-term senator from Illinois as an agent of change.

"I am here to report that my bet has paid off," he said.  "My faith in the American people has been vindicated because everywhere I go, people are standing up and they are saying, we are ready for change, we want something new, we want to turn the page and write a new chapter in American history."

The Wall Street Journal-NBC News poll found a majority of voters favor a president who will bring change over one who is more experienced and tested.

Despite that apparent advantage, Obama finds himself in a competitive race with Senator McCain.

McCain ran an underdog campaign of his own to clinch the Republican nomination, spurred by a comeback victory in the New Hampshire primary in January.

McCain emerged victorious, despite lingering skepticism from some conservatives who doubt his commitment to their causes.

McCain will try to make the election about experience.  McCain will cite his years of service in the military and in Congress, and he will question Obama's experience in national security and foreign policy issues.

McCain will also focus on his differences with Obama over the war in Iraq.  Obama wants to begin withdrawing U.S. troops once he takes office, while McCain insists the United States must remain in Iraq until victory is achieved.  

"We have incurred a moral responsibility in Iraq," he said.  "It would be an unconscionable act of betrayal, a stain on our character as a great nation, if we were to walk away from the Iraqi people and consign them to the horrendous violence, ethnic cleansing, and possibly genocide that would follow a reckless, irresponsible and premature withdrawal."

The main battle lines of the general-election campaign are already becoming clear. 

"The Democrats are going to say John McCain is George W. Bush's third term no matter how he tries to distance himself," explained longtime political observer Tom DeFrank of the New York Daily News, who was a guest on VOA's Issues in the News program.  "And the Republicans are going to paint Barack Obama, in the words of one of them recently to me, as just another loony leftist, and they are going to try to paint him as an ultra-liberal, naïve, inexperienced and therefore risky choice in a dangerous world.  And I think that is how it is going to sort out, one way or the other."

While Obama leads McCain in the polls, he must shore up support among white men, suburban women and independent voters.

Meanwhile, McCain appears to be hurt by the generally negative views of President Bush in recent polls and the fact that about seven in 10 Americans believe the country is headed in the wrong direction, especially on economic issues.

"There is a general tilt to the Democrats in the election, which you see in all of the generic [polling] numbers, whether you ask about Congress or the presidency, or President Bush's numbers," noted John Fortier, an expert on politics at the American Enterprise Institute, and a guest on VOA's Encounter program.  "That is going to be tough for Republicans and John McCain.  But, on the other hand, Republicans have ended up with a good nominee, John McCain, who runs ahead of his party and might be able to make up some of those differences, and that is why I think we see a relatively competitive polling set of numbers between Obama and McCain."

Experts say Obama will have an advantage if he keeps the election debate focused on change and addressing the weak economy.  McCain would prefer to focus on national security, the war on terrorism and the issue of experience.

Stuart Rothenberg is a non-partisan political analyst based in Washington.  He also was a guest on VOA's Encounter.

"I think one of the key groups could be personality voters," he explained.  "They are casual voters, they are younger voters, they are newer voters.  They are going to get swept up in some of the Obama excitement, and this is a problem [for Republicans], people who want change.  They do not even know what they mean by change, but they know they do not like the way things are now.  I think this is the big Republican problem because while McCain will say that he favors change as much as Obama does, when you look at the two candidates and you look at the two parties, it is simply a harder argument for McCain to make."

Much of the general election debate is expected to focus on the domestic economy and the war in Iraq.  Other issues that could figure prominently include terrorism, illegal immigration, the home mortgage crisis and the environment.

Obama is to be confirmed as the Democratic nominee at the national nominating convention in Denver in late August.  McCain will be officially nominated at the Republican convention the following week in Minneapolis-St. Paul.