(AP) - Barack Obama aims to weave the personal with thepolitical Thursday night as he tells 75,000 supporters in afootball stadium - and millions more at home - how as president hewould make a difference in their lives.

Click for Long Islanders' reaction to Obama?s nomination

The Republicans weren't just sitting back to watch on TV. GOPrival John McCain stayed mum about his running mate deliberations,but one top prospect - Minnesota Gov. Tim Pawlenty - abruptlycanceled numerous public appearances, as speculation increased inintensity.

McCain was expected to announce his decision by week's end,possibly Friday, hoping to take the edge off Obama's big conventionfinale.

Obama put finishing touches on his speech Thursday morning, butalso found time to shoot some hoops on a basketball court at theDenver Athletic Club.

He also spoke to a luncheon for female Illinois delegates. "Ihad this speech tonight. I wanted to practice it out on you guys.See if it worked on a friendly audience," Obama joked. He didn'tactually give the speech.

"I haven't forgotten where I came from," he added. "It'sbecause of all of you that Michelle and I have this great honor ofhelping to lead the party and win back this White House."

Aides said his address accepting the Democratic presidentialnomination would be a "direct conversation" with Americans onwhat's at stake and the risks of putting another Republican in theWhite House.

Obama, who first gained national prominence just four years agoin a speech to the 2004 Democratic Convention as a little-knownIllinois state senator, was also expected to draw contrasts withrival John McCain and try to dispel any remaining concernsAmericans might have about his capability to govern.

Obama accepts the Democratic nomination Thursday night atDenver's Invesco Field at Mile High.

Three hours before the day's program began, as many as 1,000people were lined up at a pedestrian entrance to the stadium. On ahot, sunny day, security people were advising the crowd to drink alot of water. Nearby street parking was going for as much as $80 aspace.

"Senator Obama's speech tonight will be as he himself hascharacterized it, more workmanlike, a very direct conversation withthe American people about the choice we face in this election.About the risk of staying on the same path we're on, the risk ofjust more of the same versus the change we need," Obamaspokeswoman Anita Dunn said in a conference call with reporters.

McCain appeared poised to name his running mate soon after theend of the Democratic convention, in hopes of curbing any bump inthe polls that Obama might get as he and running mate Joe Biden andtheir wives begin a three-day bus tour of battleground states onFriday, beginning in Pennsylvania.

McCain, too, planned a rally in Pennsylvania, on Saturday.

He said in a radio interview that he was bringing to that eventboth former Pennsylvania Gov. Tom Ridge and former MassachusettsGov. Mitt Romney, two of the leading names on his short list forvice president. But he cautioned against assuming that meant eitherone would be the pick.

"I haven't decided yet, so I can't tell you," he told KDKANewsRadio in Pittsburgh in an interview that was taped onWednesday.

Pawlenty, who was in Denver as part of a GOP team criticizingDemocrats, deflected all questions about the possibility of beingMcCain's vice presidential pick. "I am scheduled to be inMinnesota tomorrow to be at the State Fair," was all he would sayabout his immediate plans.

Without explanation, Pawlenty called off an Associated Pressinterview at the last minute, as well as other media interviews inDenver, site of the Democratic National Convention.

Others believed to be in contention for the No. 2 slot on theGOP ticket included former Massachusetts Gov. Mitt Romney, who wasmeeting with donors in California, and Democrat-turned-independentSen. Joe Lieberman of Connecticut, who was vacationing on LongIsland.

Both campaigns see Pennsylvania as an important battleground.

"This is not hyperbole: We cannot win without Pennsylvania,"Biden, who spent part of his youth in Scranton, Pa., toldPennsylvania delegates at a breakfast Thursday.

Obama hopes Biden's blue-collar appeal will let him avoid arepeat of his Pennsylvania primary loss in the Democratic primaryto Hillary Rodham Clinton.

Obama stood ready to accept the Democrats' nomination, the firstblack person to claim such a prize, on the 45th anniversary ofMartin Luther King Jr.'s historic "I Have a Dream" speech. The Democrats officially made Obama their presidential choiceand Biden their vice presidential nominee on Wednesday.

The McCain campaign said it planned to air a new ad that willrun in battleground states Thursday night around the time ofObama's address. In it, McCain will look into the camera and speakas if he were talking directly to Obama, said McCain spokeswomanJill Hazelbaker.

Obama played basketball Thursday morning at the Denver AthleticClub. He waved to supporters as he came out, wearing a SecretService cap, a brown shirt and athletic pants.

He was also doing some final work on his speech, said campaignspokesman Dan Pfeiffer.

"Doing the speech at Mile High is an important point for ourcampaign. It's symbolic of how Sen. Obama won the nomination. Itwill show how Obama wants to involve people who are not usuallyinvolved in the political process," Pfeiffer told reporters.

Republicans, keeping up a theme they first used when Obama drewtens of thousands for an appearance in Berlin, derided theacceptance speech's stage as befitting a celebrity with littleactual accomplishment.

"This Roman-like facade, a facade with Roman columns, is aperfect metaphor or icon for the point that it's an interestingproduction, but behind it there's not much there," MinnesotaRepublican Gov. Tim Pawlenty told ABC.

Democrats have responded by noting that President Bush'sacceptance speech in 2004 also took place on an elaborate stagethat included similar columns.

The drama of Obama's long, emotional primary struggle againstClinton behind him at last, the Illinois senator's conventionspeech will propel him into a tough sprint to Election Day.

A modern-day technological effort was under way to get most ofthose packed into the stadium to form the world's largest phonebank - text-messaging thousands more to boost voter registrationfor the fall.

Obama accepts his party's nod on a day few might have imagineddecades ago, when King fought for civil rights.

"This is a monumental moment in our nation's history," MartinLuther King III, the civil rights leader's eldest son, told TheAssociated Press on Wednesday. "And it becomes obviously an evengreater moment in November if he's elected."

Obama was just 2 years old when King addressed a sea of peopleon the National Mall in Washington on Aug. 28, 1963.

Adding a touch of celebrity to the convention's final night,singers Sheryl Crow, Stevie Wonder and will.i.am were scheduled toperform, with Academy Award-winner Jennifer Hudson singing thenational anthem.