Yes, the stop Trump movement lives on—for the moment—with various conservative organizations and personalities taking the lead. Meanwhile, former rivals like New Jersey Governor Chris Christie and neurosurgeon Ben Carson have endorsed Trump, as have Florida Governor Rick Scott and former GOP Vice Presidential candidate Sarah Palin. More endorsements will follow, and when Trump passes the 1,237 delegates necessary to win the nomination, it’s likely that most Republican politicians will fall into line behind him. Here’s why.

People are seemingly hard-wired to associate with and embrace success. This behavior may have an evolutionary basis. For a person’s genes to survive into posterity, it’s better for that individual (or creature) to be able to identify and then be part of the tribe or group that was going to triumph in struggles for survival. That is why people tend to automatically respond positively to displays of strength. And our preference for strength may also help explain why people tend to select male over female leaders and to prefer taller men and women for leadership positions.

The classic basking-in-reflected-glory research showed that university students were more likely to wear clothing items with their school logos following a football victory than following a defeat—even though the people themselves had no direct responsibility for the games’ outcomes. The explanation: To feel better about themselves—to self-enhance—people sought to symbolically identify with success by adorning themselves with successful school’s insignias.

Of course, politicians not only share this desire to be on the winning side and to be close to success and status, they also seek jobs and career advancement. Those who hold powerful positions provide others the possibility of access to jobs, information, public events, and other resources. That is why even rivals and ideological opponents often fall into line behind adversaries once those adversaries triumph.

Moreover, people change their positions on politicians and products all the time. Marketing research provides evidence of two psychological mechanisms that make supporting even unethical or immoral political figures—let alone just divisive or unattractive individuals—possible. Moral rationalization gives people the freedom to say that transgressions aren’t that bad. So, for instance, if Trump exaggerates his capabilities and demonizes minority groups, one rationalization would be that politicians do such things all the time and that Trump’s behavior isn’t that far outside the norm. Moral decoupling allows people to maintain that some inappropriate behavior is not relevant when making judgments about someone’s competence in another domain. For example, the thinking goes, Trump’s aggressive language may not be relevant to his ability to get things done. In fact, his demeanor could signal that he may be more competent in negotiating better deals with trade partners and political adversaries. Moral decoupling and moral rationalization permit people to support politicians who do bad things; the desire to be close to winners provides the motivation to engage in such reasoning.

None of this is suggesting that such tendencies are ideal or recommended. But such behavior is common. So don’t be surprised when seemingly intractable opponents flock to Trump and even seek to curry his favor once he has locked up the GOP nomination. This behavior is common in politics and in business—for some potent psychological reasons.

Jeffrey Pfeffer is Thomas D. Dee II Professor of Organizational Behavior at the Graduate School of Business, Stanford University and author of Leadership BS: Fixing Workplaces and Careers One Truth at a Time.