A large share of North Carolina’s registered Latino voters is still undecided in the state’s U.S. Senate race and says immigration is its biggest concern, according to Hispanic group’s new poll.

The poll done by Latino Decisions for the National Council of La Raza Action Fund, an arm of NCLR, found 40 percent of registered Latino voters surveyed favored Democratic Sen. Kay Hagan and 15 percent favored Republican challenger Thom Tillis.

Of the 45 percent who said they were undecided, 12 percent leaned toward Hagan and 7 percent leaned toward Tillis.

“Comparatively, the number of undecided Latinos in North Carolina is much larger than we’re seeing in other states,” said Matt Barreto, Latino Decisions cofounder.

Although Latinos have been in the state for many years, North Carolina has experienced heavy growth in its Hispanic population over the past couple of decades, with its immigrant community becoming well established in places such as Durham.

A third of those surveyed in the poll said they had been contacted by a party, candidate or organization about voting. Barreto said his company’s research shows that Latinos contacted about voting have turnout rates equivalent to white and black voters.

About 31 percent of the Latino electorate turned out in 2010.

The Hagan-Tillis race is one of the more competitive of the 2014 election cycle. The Latino vote in some of the Senate races has been an election uncertainty after several senators, including Hagan, asked the president to delay taking executive action on immigration to keep the immigration issue out of the campaign.

The poll found that 33 percent said immigration issues were their most important concern as they decided who would get their vote. Economy, 28 percent and health care, 22 percent, followed.

“This is the first time we’ve seen this pop out as the number one issue in any of the polling we’ve done,” said Matthew McClellan, NCLR Action Fund executive director.

Latino Decisions polled 400 occasional registered Latino voters in English and Spanish by cell phone, landline and through an online panel. The margin of error of the poll is plus or minus 4.9 percentage points. NBC News does not use online components in its political polling, though Barreto said they help reach younger voters.