In the U.S. presidential race, the next major test for Democratic rivals Barack Obama and Hillary Clinton will come in primaries in North Carolina and Indiana on May 6.  Clinton hopes to build momentum after her decisive primary victory this week in Pennsylvania, while Obama seeks to broaden his appeal among various voter groups where Clinton has demonstrated an advantage.  VOA National correspondent Jim Malone has more on what is ahead in the presidential race from Washington.

Indiana in particular is shaping up as a crucial battleground state in the fight for the Democratic Party's presidential nomination.

Barack Obama is favored in North Carolina, which also votes on May 6, largely because of the state's expected heavy turnout by African-American voters.

But the polls in Indiana show a tight race between the two Democrats, and an Obama victory there could go a long ways toward easing the doubts of some Democrats who may be questioning whether Obama would be the strongest Democrat in November against the presumptive Republican nominee, Senator John McCain.

Political analyst Norman Ornstein of the American Enterprise Institute says Hillary Clinton has an uphill climb to the Democratic nomination, even with her convincing win in Pennsylvania.

"So she is going to have to change the dynamic in a different fashion to make herself a stronger candidate," Ornstein said. "And until I see a collapse of Obama in North Carolina and a collapse in Indiana, I remain deeply skeptical that she has a path to this nomination."

Obama continues to lead in the overall delegate count and in the number of popular votes won through the 45 caucus and primary contests held so far.

Nine contests remain, and most experts believe Obama will retain his lead in the delegate count, though Clinton may be able to reduce his margin in the popular vote.

But analysts say the recent vote in Pennsylvania is the latest example of a disturbing trend for Obama, his inability to win over working class white voters.

"It clearly shows that Obama has yet to prove that he can appeal to white working class voters, which can be important swing votes in the general election in states like Ohio and Pennsylvania," said John Fortier, who monitors political trends for the American Enterprise Institute.

Clinton supporters say Obama's difficulty in winning working class or so-called blue-collar voters could doom Democratic prospects in the November election.

But at this point, most experts believe the only way for Clinton to win the nomination is to convince the remaining uncommitted party officeholders and activists known as superdelegates that she would be the better nominee, even though she will likely trail Obama in delegates and popular vote won when the primary season ends on June 3.

Neither candidate is likely to win enough delegates to claim the nomination outright, so the roughly 300 remaining uncommitted superdelegates are expected to play a crucial role in the outcome of the nomination battle.

"Put yourself in the mind of a superdelegate," said analyst Norman Ornstein.  "Will you enhance the chances of Democrats winning this presidential election if you deny the African-American candidate who has won more delegates, more votes and more states the nomination, based on a theory Hillary Clinton would the stronger nominee in the Fall?  The only way that would happen is if you have stunning, startling shall I say, poll results showing that she would win or do sizably better than Obama."

In fact, recent polls suggest that both Clinton and Obama would be competitive against McCain with no clear advantage for either Democrat.

University of Virginia expert Larry Sabato says Clinton may have bought herself more time and fundraising with her win in Pennsylvania, but perhaps little else.

"Obama, as everyone says, he has failed to close the deal," Sabato said. "He seems unable to consolidate the party, partly because of the continuing challenge from Clinton.  And that pushes back the decision time to June at the earliest.  That is when the party poobahs [leaders] and the superdelegates conceivably will coalesce and make their final decision, probably for Obama.  Obama will still have a tough task in front of him, and that task is the consolidation of the Democratic Party base."

The bitter and much longer than anticipated Democratic race may also be helping McCain.  He has pulled nearly even with both Obama and Clinton in recent polls, and experts like Larry Sabato believe McCain will benefit down the line from the attacks being leveled by the Democrats at each other now.  

"The truth is, it is not helping," he said. "It is hard to make the case that this is a positive step in the Democratic direction, though it is toughening up Obama.  I mean, no one has entered presidential politics with less experience than Obama, so this is a good thing for him in that sense."

Once the Democrats agree on a presidential nominee, the polls suggest that voter attitudes and concerns about specific issues should play to the advantage of the Democratic candidate.

Nearly 70 percent in a recent poll disapprove of President Bush.  That combined with growing concern over the economy and a desire to draw down the number of U.S. troops in Iraq could create a tough election climate for Republican John McCain.

Despite all that, public opinion expert Karlyn Bowman says McCain is showing surprising resilience in recent surveys that suggests the infighting between Democrats Clinton and Obama may be taking a toll.

"Democrats are still winning the enthusiasm contest, they are clearly winning the [voter] turnout contest, they are winning the money contest, they are winning the congressional recruitment game, and they are also winning the expectations game.  McCain's strength in the face of all of this is quite impressive," she said.

The Democrats hold their national nominating convention in Denver in late August, while the Republicans hold their convention in Minneapolis-St. Paul in early September.