1. The man is a robot, at least he comes across that way to the public he is trying to persuade to vote for him. History shows Americans usually vote for the candidate they would most like to go out and have a beer with. One has to back to the 1970's to find exceptions to this rule.
2. He is unable to tell voters what he stands for. Voters like to know their candidate has some passion and commitment to his values. Romney has none of this. Conservative commentator Joe Scarborough says that a friend of his who is a prominent Republican governor met with Romney and asked him three times why he wants to be president. He never could articulate a meaningful sentence as to why he wants the job, or what he wants to accomplish as president.
3. He is unable to convince true conservatives he is one of them, while at the same time mouthing conservative platitudes which do nothing to convince the crucial voters in the middle to vote for him.
4. He is unable to answer simple questions, as when he went on "Face the Nation" (the first non-FOX interview he's done in this campaign), and could not answer a simple question about whether he would continue the recently-announced Obama policy of not deporting illegals who came here as children and are being productive, law-abiding residents of this country. Bob Schieffer had to ask him five times (!), and he never was able to answer. Romney said he would put into place a long-term solution. Two problems with this. First, Romney refused to give any details of what this so-called "long-term solution" would consist of; and second, he seemed oblivious to the reality that getting any immigration bill through Congress was unlikely, given the partisan divide in Washington these days. Schieffer pressed him by asking, "But would you leave the policy in place while you pursued your long-term solution", and Romney still could not answer. I think the American voters, while not sophisticated, can recognize stonewalling when they see it, and reject it.
5. He is obviously completely ignorant on foreign policy, as shown by his occasional statements in this regard. He wants voters to believe he is strong enough to stand up to Iran, whatever that means, when he isn't even strong enough to stand up to Rush Limbaugh! Voters are smart enough to see through this.
6. His refusal to release his tax returns leads to inevitable speculation that he is hiding something. The irony here is that his own father, George Romney, pioneered the policy of releasing multiple years of tax returns, saying that one year can be a fluke, and only by releasing many years of returns can an accurate picture be had. Initial speculation was that he had paid no taxes in 2008 and 2009, after the collapse of the financial market. Now, Harry Reid says on the Senate floor that he heard there were ten years of no taxes paid whatsoever. Whether Reid is right or not is irrelevant; the point is that Romney has it within his power to clear this up in an instant, and has refused to do it. All commentators, Dem. & Rep. alike, say he should have done it along ago and got this out of the way, so that the campaign could focus on the real issues. Romney is tone-deaf on this issue.
7. If the election ever does get close enough to be in doubt, the Democrats will have in the can and ready to go TV spots which will highlight Romney's many flip-flops and gaffes. Just about anything Romney has said can be refuted by Romney's own statements in the past. No candidate can survive this type of withering onslaught.
8. He gives no details as to how he intends to accomplish any of his campaign promises. Here is a partial list of promises for which no details have been given: create 12 million new jobs; stop Iran for getting nuclear weapons; enact comprehensive immigration reform; enact comprehensive tax reform; balance the budget even while cutting taxes for the wealthy and increasing military expenditures. This lack of detail is reminiscent of Richard Nixon's promise in 1968 that he had a "secret plan" to end the Vietnam War. Of course, there was no secret plan and the war dragged on four more years. And recently it has come out that Nixon actually sabotaged pre-election peace efforts, because he feared that a pre-election peace would cost him the election!