"I've examined this race in every possible way, and I keep returning to the same fundamental conclusion: If I run, the likely result would be a brutal and highly negative Democratic primary — a primary where the winner emerges weakened and the Republican strengthened. I refuse to do anything that would help Republicans win a Senate seat in New York, and give the Senate majority to the Republicans. I realize this announcement will surprise many people who assumed I was running. I reached this decision only in the last few days — as I considered what a primary campaign, even with the victory I saw as fully achievable, would have done to the Democratic Party. I am a Democrat. But I am an independent Democrat. I am not going to stop speaking out on behalf of policies that I think are right — regardless of ideology, party or political expediency."
I think what he means by all his wordiness is that people don't like him and they wouldn't vote for him. At least, that's what I get out of it.
Sidenote: when I lived in California, there was a very prominent Ford dealership called Harrold Ford, and every time I hear about Harold Ford, politician, I think Harold Ford used car salesman.
It isn't a big stretch.