There are several reasons. First, creating an organization and spending millions of dollars to carpet-bomb Trump with negative ads in key states isn’t easy; there aren’t many people who could pull it off. Second, some donors think an anti-Trump offensive not only would not work but would backfire on an already unpopular GOP establishment. Third, some who do believe it could work think it should not be attempted until Trump’s critics have agreed on an alternative candidate — which they haven’t. Fourth, the anti-Trump opposition can’t decide who should lead such an effort. And fifth, most GOP strategists and money movers continue to believe Trump will ultimately fail on his own, that in the end he will not be the Republican nominee.

“The problem with organizing an anti-Trump effort amongst big GOP donors is the immensity of it,” said a former Romney fundraiser in an email exchange. “It would require real leadership, huge time commitment, huge oppo research effort, and massive $$s. This is not something one person with $10 million to $20 million to burn can accomplish. It needs the leadership of an organization already geared toward such an effort. Think Koch, Rove, etc.”…

Despite all that, there are some strategists who believe an anti-Trump campaign could still work. In a phone conversation Sunday, Stuart Stevens, chief strategist for the Romney 2012 campaign, said he is mystified that some other campaign — the still-rich Jeb Bush super PAC, for example — hasn’t dropped a huge negative advertising bomb on Trump. “Look at Iowa,” Stevens said. “The fact that someone who has been married three times, bankrupt four times, is in the gambling business and has speculated publicly about the possibility of dating his daughter is a leading candidate is absurd. I think 10,000 ratings points [a technical description for a major ad buy] would completely reorient voters to facts that are relevant.”