Asian-Americans make up the racial or ethnic group that has shifted most strongly toward the Democratic Party since 2000. They are also the country’s fastest-growing racial or ethnic group by percentage.

Researchers at Gallup think part of the shift stems from many Asian-Americans’ affinity for President Obama, a fellow member of a minority group who spent part of his childhood in Asia. But Gallup says the move toward Democrats also reflects many Asian-Americans’ opposition to core tenets of the Republican party — which suggests major challenges for Republicans in winning over the group.

In 2008, 62 percent of Asian-American voters backed Mr. Obama. In 2012, the number jumped to 73 percent, according to Edison Research exit poll data.

Religion also plays a role, according to Gallup’s analysis, which was released Friday at the annual conference of the American Association for Public Opinion Research in Anaheim, Calif. A majority of Asians in the United States are non-Christian, and many are not particularly religious. A party that has evangelical Christians as a core constituency, as the Republicans do, has the potential to alienate Asian-Americans.