Americans’ aversion to voting for Mormons has spiked since Mitt Romney’s first presidential bid in 2007 — and that the people most wary of Mormon candidates are not Evangelicals, but rather political liberals and non-religious voters, according to new research from a leading scholar of anti-Mormon attitudes.

The overall increase in anti-Mormon attitudes among liberals may be an unanticipated consequence of the “the continuing candidacy of Mitt Romney and Mormon activism against same-sex marriage,” the study suggests. And its findings may be alarming to the Romney campaign because among the study’s other findings is that voters’ perceptions of Mormonism are closely tied to whether they’ll vote for him.

According to American National Election Studies, nearly 35 percent of national respondents said in February they were “less likely” to vote for a Mormon. That’s up nine points from 2007, when Pew found 26 percent of voters expressing concern about pulling the lever for a Latter-day Saint.