It’s easy to see why many foreign policy experts would be reluctant to sign on to the Trump campaign. In fact, earlier this month dozens of prominent Republican national security experts signed an open letter declaring their opposition to a Trump presidency, arguing that a Trump administration “would use the authority of his office to act in ways that make America less safe, and which would diminish our standing in the world.”

As the primaries drag on and Trump moves to consolidate support for the GOP nomination, some parts of the GOP establishment will no doubt begin reconciling themselves to Trump. There are some indications that this is already happening.

For foreign policy experts, who tend to be careerist and sensitive to their reputations, this presents an especially difficult choice. Trump’s opinions about America’s role in the world are so far outside the mainstream that signing onto his campaign could meant the end of an adviser’s career. It would be like a professional economist endorsing Trump’s call for a trade war with China—no serious expert could do it with a clear conscience.

Since Trump is unlikely to find foreign policy experts that share his outdated nationalism, it remains to be seen what role these advisers will play other than to allow Trump to say he’s talking about foreign affairs to someone other than himself.