President Barack Obama’s healthcare law may have been responsible for pushing whites to vote Republican and polarizing the country at historic levels, according to a new Gallup analysis.

On the four-year anniversary of Obamacare, the implication of the Gallup study is that Obama’s policies–not his race or personality–have been the impetus for the increasing level of racial polarization. 

The Gallup study found that in 2010, “nonwhites’ net party identification and leanings showed a 49-point Democratic advantage, and whites were 12 percentage points more Republican than Democratic.” That “resulting 61-point racial and ethnic gap in party preferences is the largest Gallup has measured in the last 20 years.”

“It is unclear precisely what role Obama’s race has played in these changes. However, the shifts do not appear to be an immediate reaction to his becoming president,” Gallup wrote. “Whites became slightly more Republican during 2009, the first year of Obama’s presidency. However, the biggest movement came during the next year, when Obama signed the healthcare overhaul into law.” This is when he “saw his approval rating sink and his party lose its large majority in the House in that year’s midterm elections.”

The level of overall racial polarization has increased during Obama’s presidency. The study found that the average party preferences for nonwhites have consistently shown a “roughly 47-point Democratic advantage under Clinton, Bush, and Obama.” During the same time, however, “whites have become increasingly Republican, moving from an average 4.1-point Republican advantage under Clinton to an average 9.5-point advantage under Obama.” 

“During the last few years, those racial and ethnic divisions have grown, mostly because whites have drifted more toward the GOP,” Gallup concluded. “Thus, party preferences by race during the Obama years, though similar in nature to the past, have seen some movement that has resulted in slightly greater racial polarization than before.”

The study found that after the historic Tea Party-fueled midterm elections that gave Republicans back their House majority in 2010, whites are “somewhat less likely to align with the Republican Party now than they were in 2010 and 2011″ when the GOP became more moderate. Republicans, though, still show a “roughly 10-point advantage” among whites, which Gallup noted will “remain the majority racial group in the U.S.” Those numbers may favor Republicans in midterm elections, but the study also noted that Democrats’ “decisive advantage among racial and ethnic minorities allows them to more than offset the Republicans’ advantage among whites” in national elections.