The abuse he suffered from disillusioned fans after Saturday's home defeat by Liverpool, plus Jurgen Klinsmann's criticism of him at the weekend, fuelled Sugar's outburst.
Francis said: "It is Alan's prerogative if he wants to up and go. Does he mean it? You had better ask him, but I know he's hurt and surprised that this has come so quickly - just three games into the season.
"We will get players back from injury and we will bring new ones in as well. It is a question of time, but nobody is interested in that. All they want is to see results.
"I don't know who else out there could do the same as Alan has done for the club, especially financially. Not many I suspect. When Alan came in a few years ago the whole club needed stabilising financially and he's done that. People should not forget, but they seem to do so."Reuse content