“I acknowledge reality. There’s going to be three or four candidates remaining after New Hampshire,” said former Minnesota Rep. Vin Weber, a Jeb Bush adviser who also worked on George W. Bush’s presidential campaigns. “I think the field is going to narrow pretty quickly. We’ll see what happens in South Carolina, and from there you can see the dynamic starting to winnow the field pretty quickly.”

While Weber said he would remain with Bush as long as he was in the race, others said they may soon head for the exits. Barring a strong showing, they said, Wednesday could be a day of deep reflection for them.

“If he doesn’t do well in New Hampshire, I think he needs to think long and hard about what he wants to do,” said one top Bush fundraiser who played a key role in his brother’s administration.

Another high profile Bush financial backer, who has also been close to the family for years, said most of Bush’s donors would give him until the South Carolina primary on Feb. 20. “That’s when they say, ‘Enough.’”