Barack Obama took a lot of ribbing for setting up Greek columns on the larger-than-life set of his nomination acceptance speech in Denver two months ago. But at least he knew for certain then that when the ballgame was over -- he was going to be the Democratic candidate for president. Now, with the Nov. 4 general election still 12 days away, the front-running Illinois senator is planning an Election Night celebration that could put his Invesco Field party to shame. A huge stage is being constructed in Chicago's Grant Park, where Obama hopes to declare victory before a cheering throng that could dwarf the one at the Democratic convention. Back then, "only" 80,000 fans were in attendance that night. This time, it could be hundreds of thousands in the park and its surroundings -- closer to Berlin in July than Denver in August. The Chicago Sun-Times reports the price tag of the fanfare has been pegged at $2 million, to be picked up by the Obama campaign. Mayor Richard Daley reportedly suggested Obama use a cheaper venue, but was turned down. Obama is well on his way to winning the election, according to most polls and electoral vote projections. The campaign may be preparing to set the champagne on ice. But it may want to heed the usual reminder: As Yogi Berra famously said, it ain't over till it's over. An Obama victory -- he would become the first African-American president -- would logically be cause for an historic celebration. So far, the campaign's staying mum on the expected crowd count. Asked how many people the campaign was anticipating in Grant Park, Obama spokesman Tommy Vietor quipped, "At least 10." "We have a lot of supporters who have given their time and effort to the campaign, and we want them to share in the election night with us," Vietor told FOXNews.com. The excitement is palpable at Obama's rallies, a tone the candidate has reflected. "I feel like we got a righteous wind at our backs here," Obama told supporters in Leesburg, Va., Wednesday evening. But John McCain -- and Obama himself -- are warning the Democrat's supporters not to get ahead of themselves. McCain says he savors being the underdog so close to Election Day, and for weeks he has accused Obama of "measuring the drapes" and counting him out. "My opponent's looking pretty confident ... these days," McCain said Wednesday in Goffstown, N.H. "He'll be addressing the nation soon. He's got another of those big stadium spectacles in the works. But acting like the election is over, it won't let him take away your chance to have the final say in this election." Obama is making an effort to catch himself and couch his language when he talks about post-Election Day plans. He is warning supporters not to get lazy and "screw it up," as he says Democratic campaigns have been known to do. "We're going to have to work, we're going to have to struggle, we're going to have to fight for every single one of those 12 days," Obama told the crowd at an Indianapolis rally Thursday. "It's not going to be easy, but I'm hopeful about the outcome ... but we cannot let up." Vietor brushed aside McCain's criticism that Obama is being too presumptuous. "That's ridiculous. We're working hard every day to talk to voters, to get out the vote and knocking on doors. This is a campaign that went through one of the longest primaries in history, and rest assured we take nothing for granted," he said. He said the Grant Park event will be free and open to the public. As for McCain, he's holding his election night festivities at the Biltmore in Phoenix, which customarily hosts weddings and business retreats. Compare that with Grant Park, which customarily hosts the rock mega-concert Lollapalooza. Also by contrast, only a select group of reporters will be allowed to witness McCain's speech. Due to limited seating, the rest of the media on site will be watching on TV in a separate filing room. With a theoretically limitless outdoor capacity, the press are invited to attend Obama's event. While there's no fee outright to cover it, news organizations have been asked to pay for prime seating and Internet and phone service. Meanwhile, Obama is trying to downplay speculation about post-election plans. He spoke about foreign policy challenges Wednesday after meeting in Virginia with his "working group" on national security. He oscillated between jabs at McCain (he said his rival's latest tax policy charges were a sign "that they have run out of ideas"), and deference to the voters who will decide the election. Asked whether he planned to attend the global economic summit scheduled for mid-November, Obama made sure to pay homage to President Bush. "Even though the election will have taken place and we will have a new president-elect, we are still going to have one president at a time until January 20th, when the new president is sworn in," Obama said. "So, you know, there is always a transition period. I don't want to get too much ahead of ourselves." He noted that his economic team has been in regular contact with the "uppermost reaches of policy-making, Secretary Paulson and Federal Reserve Chairman Bernanke." "But I don't want to make commitments at this point in terms of our participation ... before I've even won the election," he added.