It's starting to feel a little like November as the presidential primary process goes national on Super Tuesday. The Democratic and Republican candidates and their surrogates have spent the past several days engaged in a political media war and a blitz of personal appearances, working to win voter support and, most importantly, the greatest number of delegates, in the 20-plus states that will hold primaries tomorrow. "The early primaries have narrowed the field to the most credible candidates—at least in the minds of Iowa, New Hampshire, and South Carolina. Now it's a more focused race, almost like a general election," says Robert C. Smith, a professor of political science at San Francisco State University . It will be a real nail-biter of a night for Democratic contenders Sens. Hillary Clinton and Barack Obama with more than half of the delegates necessary to secure their party's nomination up for grabs. In several of the primary states, delegates are awarded proportionally by congressional district. Because delegates are allocated based on the percentage of the vote won by each candidate—rather than all of the delegates being awarded to the winner—the outcome is less predictable. In districts with an odd number of delegates, the extra delegate is awarded to the candidate who wins more votes. To make things even more exciting, Obama appears to be narrowing Clinton's lead in national and statewide polls. So, who's got the most momentum? According to many political observers, it's Obama. "The Clinton camp is probably excited that the primaries are this week and not next week because he's closing the gap pretty rapidly," says Peter Groff, a senior lecturer and executive director of the Center for African American Policy at the University of Denver . Joint Center for Political and Economic Studies senior research associate David Bositis agrees. "It would really help Obama if he had another two or three weeks to focus on the Super Tuesday states because the more he's known, and gets out there and makes those speeches … he's a killer ." Based on his research, Bositis believes that Obama will win Georgia, Alabama, and Illinois. Clinton will take New York, Arkansas, Oklahoma, and a close race in Tennessee. Toss-up states include Delaware, Idaho, Kansas, Missouri, Minnesota, and New Mexico. California, with a whopping 370 delegates, Bositis adds, will be close. "I wouldn't be surprised if either one wins it," he says. On most issues, Obama and Clinton are ideologically similar; so many Democrats will be faced with a choice between experience or change. That's where Clinton may have the advantage, according to Byron Orey, a professor of political science at the University of Nebraska-Lincoln. "Despite how negatively Americans viewed George W. Bush's presidency, in the 2004 campaign they found themselves hamstrung. Because we were in the midst of war, they were more likely to support him than to choose change. Given that, the political pendulum swings in the direction of Clinton," Orey says. He also believes the "Billary" factor, or two for the price of one, may also work in Clinton's favor. "People may recollect the economic prosperity during his presidency and compare it with the economic misery that they're faced with today; thus, experience in combination with change will trump change by itself," he adds . The conventional wisdom is that the race between the two Democrats will most likely extend until the end of March. "I expect it to be effectively a tie. Obama is going to win more states than Clinton, but she'll probably win larger states so the contest will go on," says Smith. The fact that there will be just a few primaries a week during that period will help Obama because he'll be able to spend much more time in each state and he still has a lot of money left to spend. Tuesday will be less dramatic for the Republicans. In many of the races, the winner takes all of the delegates, and Arizona Sen. John McCain continues to maintain a significant lead over competitors: former Arkansas Governor Mike Huckabee and former Massachusetts Governor Mitt Romney. Despite his lead, however, McCain still has to convince Republicans that he's a true conservative. "He's got to make the sale. California, which is not winner takes all, is especially bad for McCain because it's so gerrymandered that half of its congressional districts have virtually no Republicans in them," says Bositis. "Romney needs to start picking up some delegates even if he doesn't win some of the states. He needs to show he's making progress toward getting the nomination."