DENVER — Democrats gathering here for their nominating convention are significantly more nervous about Sen. Barack Obama’s prospects this fall than they were a month ago, and are urging him to use the next four days to address weaknesses in his candidacy and lingering party divisions from the bitter primary fight.

Obama’s aides said they had learned from what they described as the mistake of the 2004 Democratic convention — when aides to Sen. John Kerry’s campaign sought to forbid convention speakers from going after President Bush — and would use these four days to draw sharp contrasts with Sen. John McCain, particularly on the economy and McCain’s opposition to abortion rights.

“The stakes of this election will be made very clear,” said David Axelrod, Obama’s chief strategist. “We are going to define the choice.”

At the same time, acknowledging persistent voter unease with Obama, his aides said they would use speeches and presentations, including having Al Gore introduce Obama for his acceptance speech Thursday night, to offer a fuller biography and a more detailed plan of what he would do as president.

In interviews, Democrats arriving here said they remained confident that Obama would leave Denver at the end of the week in a strong position to beat McCain. But many made clear that a convention they had once anticipated would be a breezy celebration of Obama had turned into a more sober, consequential event.

This reflected a summer that they said demonstrated Obama’s vulnerabilities and McCain’s resilience, and the signs of lingering divisions between some supporters of Sen. Hillary Rodham Clinton and Obama.

“Back in June and July, I truly thought he was going to blow McCain out of the water and carry 30 or 40 states,” said Donald Fowler, a former national Democratic chairman who supported Clinton in the primary. “What has happened is that Republicans — McCain specifically — have really twisted his great charisma, this electric personality, to discredit his ability, his experience, his capacity, his judgment. I fear they are about to do to him what they did to Gore.”

Discussing the days ahead, Fowler continued: “Obama has got to do some things that will shore up his ability to lead — not just to charm, but to lead. They’ve got to give credibility to his understanding of foreign policy, his ability to deal with tough people and tough questions, and his ability to be more explicit and convincing on his health care policies and energy policies.”

Dennis McDonald, the Democratic chairman of Montana, a state that Obama is trying to win from Republicans, said this was a critical opening for Obama after a month in which polls suggested the race was tightening.

“Normally I might say these conventions are not so important, but I don’t think that’s the case this year,” McDonald said.

Confident, yet anxious

For the most part, this is a confident if slightly anxious party. And many Democrats were cheered by the choice of Sen. Joe Biden of Delaware as Obama’s running mate, saying he had the potential to help address some of Obama’s political shortcomings.

Still, Democrats said Obama should offer a concrete idea of what he would do as president, to counter the effort by Republicans to present him as a showman. And they said he had to offer a tougher contrast with McCain.

“I think in the case of McCain, they need to frame him,” said Kerry, an early Obama supporter who four years ago was this party’s presidential nominee. “Viscerally, my feeling is they’ve got to come back at him hard. And they’ve got to do more to complete the task of definition — both definition of him as well as definition of John McCain.”

And there are some things that may be beyond the control of the Obama campaign. Most pressing, Democrats said they were worried that the tensions between supporters of Clinton and Obama would spill into public view after her name is entered into nomination.

“I have a lot of doubts that this convention is going to be as persuasive as it should be because they’ve got this damn thing with Hillary,” Fowler said. “I love Hillary. … But this is the worst political decision I could imagine. This is supposed to be an Obama celebration. You’re going to get the nomination of someone who came very close to winning and you’re going to get a lot of people in there cheering and hollering and some people booing.”

Clinton’s advisers said Sunday that she would move to avoid this by meeting with her delegates on Wednesday and formally urging them to support Obama during the roll-call vote that night.

//Meet Barack Obama// (Denver)

By Chris Cillizza

(c) 2008, The Washington Post

DENVER — Day one of the Democratic National Convention is themed “One Nation” but could just as easily be called “Meet Barack Obama.” The speakers — ranging from Obama’s half sister, Maya Soetoro-Ng, to his wife, Michelle — will seek to not only introduce Obama to voters but also cast his life story as uniquely American.

While the proceedings are set to run from 8 to 11 p.m. on the East Coast, here are the key moments to tune in for:

— Nancy Pelosi: For Pelosi, the speaker of the House, her speech tonight will be a celebration of how far congressional Democrats have come since 2004. The party controls the House and Senate, and is almost certain to expand its majorities in November.

— Jim Leach: Turnabout is fair play. After Republicans announced that Sen. Joseph I. Lieberman, I-Conn., would address the Republican National Convention in St. Paul, Democrats decided to roll out Leach (R), a former congressman from Iowa, as one of tonight’s featured speakers. Leach served in Congress for 30 years before losing his Democratic-leaning district to a virtual unknown — Democrat Dave Loebsack — in 2006.

— Interest groups: Obama regularly derides influence peddlers and special interest groups while on the campaign trail. But at the party’s national convention, these groups will have their say, albeit on the first night of the festivities. Representatives for NARAL Pro-Choice America, the Service Employees International Union and the American Federation of Teachers will address the delegates Monday night.

— Craig Robinson: Obama’s brother-in-law is the newly installed head basketball coach at Oregon State University. Will he map out the X’s and O’s to guide the senator from Illinois to the presidential nomination?

— Caroline Kennedy: In paying tribute to her uncle, Sen. Ted Kennedy (Mass.), the former Obama vice presidential vetter will also provide a tangible link between Obama and the most storied family in Democratic politics.

— Michelle Obama: The candidate’s wife will have to execute a high-wire act in her address. She must make the case for why her husband is ready and able to be president. And she must stay away from the overly adulatory language that got her into trouble in February.