As Donald Trump continues his unforeseen march toward the Republican nomination, his opponents have made increasingly aggressive attempts to stop him, including a recent attack ad that featured his wife Melania Trump posing nude for GQ magazine. The ad, an attempt to appeal to the morality of Mormon voters in Utah, preceded Sen. Ted Cruz’s landslide caucus victory there on Tuesday, reinforcing suggestions that Mrs. Trump may be a political liability to her husband.

But my research suggests that Melania Trump could be a persuasive messenger in the campaign, especially among political independents. In fact, she could be more effective than Mr. Trump’s surrogate-in-chief, Gov. Chris Christie—and even more effective than Trump himself.

In a survey experiment conducted via Survey Sampling International over the last two weeks, I asked 3,150 Americans to read an excerpt of a speech praising Trump’s record as a leader. The text was always the same, but I randomly varied the identity of the speaker, as well as the accompanying image, to be Christie, Donald Trump, or Melania Trump. After reading the excerpt, respondents answered a series of questions designed to gauge support for Trump’s campaign.

Unsurprisingly, Democrats and Republicans were largely unmoved by any of the appeals. But independents who read the speech attributed to Melania Trump were more favorable to her husband, as the graph below indicates:

For example, relative to those assigned to the Christie condition, they rated Trump 12 points higher on a 100-point feeling thermometer, and were 17 percentage points more likely to say they supported his candidacy, on average.

These effects were larger among independent women: Melania Trump produced a 25-point increase in their support for Trump, relative to Christie, and a 16-point increase relative to Donald Trump himself.

This pattern is consistent with other research. In my forthcoming book, “On Behalf of the President: Presidential Spouses and White House Communications Strategy Today,” I show that public appearances of spouses both on the campaign trail and in the White House have grown more common and more strategic over time. I find that spouses can be effective political surrogates because their personal relationship with the president allows them to credibly communicate his feelings, beliefs, and character while advocating for various issues, even as they avoid explicitly mentioning public policy.

This strategy has allowed presidential spouses to garner political support while staying above the fray, and to be seen in less partisan terms by the electorate than presidents themselves. Data from the American National Election Study show that since the early 1990s, one’s partisan identification has consistently been a weaker predictor of approval for the first lady than for the president.

To be sure, amidst a presidential campaign, Melania Trump would be one of countless messengers vying for voters’ attention. Although it is easy to isolate her apparent impact in an experiment, that impact could be far more muted in a presidential campaign. Complicating matters further is that true independents are less than 10 percent of a typical presidential electorate.

Nevertheless, given that Donald Trump would be the least popular presidential nominee in many years, that he is particularly unpopular among women, and that Hillary Clinton reportedly plans to emphasize his previous statements about women, Melania Trump may be his best asset.

Lauren A. Wright is author of On Behalf of the President and a board member of the White House Transition Project. Find her on Twitter @drlaurenawright.