The only way that Barack Obama loses the election is if the American electorate is even more spiteful and ignorant than I perceive them to be, and I'm no optimist. I'm not saying this as a Democrat nor Obama supporter (full disclosure: I am both), but as a student of American elections.
Here is why Mitt Romney will not win - his only selling point is that he is the "Other Guy." Without a real agenda or personality, the Other Guy never wins. In fact, the only time the Other Guy has ever won the American Presidency in the last century and change may surprise you.
Let's take a look back. For brevity, I will skip elections in which the incumbent won, as the incumbent cannot possibly be the Other Guy.
2008 - Obama wins by building a Hope/Change phenomenon and energizing an unprecedented number of first time voters, combined with McCain shooting himself in the foot by choosing That Woman.
2000 - Gore was very much not the Other Guy, and he technically won. Beyond that though, George W. Bush was a large state governor with universal name recognition and the son of a former president. He was hardly Other Guy either, as he had been extremely famous for at least 10 years before his election.
1992 - Clinton was certainly a less-famous candidate going into the primaries, and many bigger Democratic stars sat out the 1992 election since George H.W. Bush looked unbeatable in 1991. However, during the general election, Clinton definitely had a message ("It's the Economy, Stupid"), and definitely had a massive personality. Fleetwood Mac, Rock the Vote, playing the sax on Arsenio, Clinton carved his own niche. He was the first Baby Boomer president (and Bush was the second. If Obama wins in 2012, they could conceivably be the only two since Barack is too young to be a Boomer).
1988 - George H.W. Bush - the consummate insider, George 41could have never been Other Guy.
1980 - Ronald Reagan defeated an incumbent, but by this point he had been famous for decades and a political force for twenty years.
1976- Jimmy Carter. Really the only one to come out of nowhere and win. Governor of then-backwater Georgia with virtually no national profile a couple years before the election. Of course, he was running against Gerald Ford, the only man to hold the presidency without being elected as president or vice president. Ford and Carter were both good guys, but neither of them should have been president I suppose. 1976 really should have been an epic battle between Ted Kennedy and Ronald Reagan, but it was not to be.
1968 - Richard Nixon, former vice president, hardly Other Guy material. Plus, Bobby Kennedy was the presumptive Democratic nominee but was assassinated, and LBJ opted not to run again, so Tricky Dick basically had a bye in the general election.
1960 - JFK. The Kennedys had been famous for some time at this point. It also helped that he had LBJ and Mayor Daley behind him, helping him to "legitimately" win key races in Texas and Illinois.
1952 - Dwight D. Eisenhower won. This being only seven years after World War II ended, Ike was almost certainly the most famous person alive at the time.
1932 - FDR. He was a little bit Other Guy since Hoover was massively unpopular, but FDR definitely had a strong personality and a definitive agenda that he ran on. Plus, he was governor of New York and related to Teddy, so it wasn't like he was an unknown.
1928 - Hoover. The American economy had soared in the 1920s under Republican leadership, so why would we change things up now?
1920 - Warren G. Harding. Okay, maybe he was Other Guy too, since he was virtually unknown before a crooked convention gave him the nomination after several votes. My source - Boardwalk Empire, so I assume it must be true.
So there you go. Romney has no base or supporters of his own or of his policies, he just has Republicans who want to vote for the Other Guy. So worst case scenario for Romney - he loses. Best case scenario - he wins and follows in the steps of Jimmy Carter and Warren G. Harding.
A vote for Romney is essentially "cheering for clothes," as Jerry Seinfeld famously quipped. I've done the same, of course. I voted for John Kerry, Other Guy extraordaire. When I was a kid, I rooted for Walter Mondale and Michael Dukakis, total Other Guys. Of course, Other Guy theory stood strong in those days, as it shall again. There was no President Mondale, President Dukakis, President Kerry, nor will there be a President Romney.