(Reuters) - Since 1968, North Carolina has backed only two Democrats for president: Jimmy Carter in 1976 and Barack Obama in 2008.

President Joe Biden visits the southeastern state on Thursday for the third time this year, betting he can do it again for Democrats in the 2024 election.

But opinion polls suggest Biden will have a tough time flipping North Carolina in this year's rematch against Republican Donald Trump. While winning the presidency in 2020, Biden lost the state to Trump by 1.3% - just 74,000 votes - his narrowest state loss.

Biden's campaign is spending heavily on early advertising, voter outreach and in-state staff, hoping to ride North Carolina's recent population boom to victory.

Some 400,000 people have moved to North Carolina since 2020, census figures show, including many people of color and with college educations, groups that vote overwhelmingly Democratic.

This time, the state's Republican party is embracing far-right candidates and policies. Its candidate for governor, Mark Robinson, has supported an outright ban on abortion and referred to homosexuality as "filth." Democrats believe those hard-line policies can help Biden.

"We are in the best position to win this state in years," said Aisha Dew, a Biden supporter and Democratic candidate for the state legislature.

The polls, however, show a tougher path for Biden in the November election. An Emerson College poll released on Tuesday showed Trump five points ahead of Biden in the state, while Marist College polling from March showed Trump leading on issues like immigration.

With a hefty 16 votes in the 538-vote Electoral College that selects U.S. presidents, North Carolina would be more than a historic flip. Winning the state could be an insurance policy for Biden, who polls show struggling against Trump in other battleground states.

A win in North Carolina could help Biden clinch victory even if he loses Arizona, Georgia or Wisconsin, states he won in 2020 and where polls show close races this year.

The Biden campaign has poured $30 million into battleground state ads since early March, including in North Carolina, aimed at groups including Hispanics and African Americans.

It has been working with state election officials to pre-qualify a list of acceptable identification for voters, the first statewide election requiring a photo ID to vote in person.

North Carolina's Republican-led legislature has passed some of the strictest laws in the U.S. that could limit whose vote counts. Republicans say these are needed to prevent voter fraud; Democrats say they are meant to suppress likely Democratic votes.

Biden's campaign has opened 11 offices in the state and had 40 staffers by the end of the April, aides say, a sharp contrast to Trump, who has yet to name a state team or open any offices in a state he visited more than 20 times in 2020. Trump visited North Carolina earlier this year but had to cancel a rally there last month due to storms.

Trump's campaigning has been limited because he on trial in New York, accused of falsifying business records to conceal hush-money payments to a porn star during the 2016 campaign.

Biden visits Wilmington, North Carolina, on Thursday to talk about $3 billion in federal funding to replace lead pipes across the country.

Republicans say they are not worried.

"In 2016 and 2020, Democrats lit money on fire in North Carolina only to lose to President Trump," Anna Kelly, a Republican National Committee spokesperson, said in a statement.

RALEIGH, CHARLOTTE ARE KEY

North Carolina's population boom has been led by people of color, according to state budget figures, and is most pronounced around the banking hub of Charlotte and the state capital Raleigh, two of the fastest-growing metro areas in the U.S.

Many of the new residents are from Democratic-leaning states like New York and California, according to researchers at the University of North Carolina at Chapel Hill.

Mecklenburg County, encompassing Charlotte, and Wake County, including Raleigh, have added a net 90 voters a day for the past four years, accounting for 41% of the state's new voter registration growth for the period, said Paul Shumaker, a long-time Republican pollster in North Carolina.

"This is the county where the election is going to be won," Mecklenburg County Democratic party chair Drew Comer told supporters when Vice President Kamala Harris visited.

In 2020, Biden beat Trump by 198,896 votes in Mecklenburg County and 167,139 in Wake County, even as he lost the state.

Despite the population boom, there are signs of trouble for Democrats. Black turnout in the 2022 midterm elections was below that of the previous midterms in North Carolina, which at 20% has one of highest Black populations in the country.

Even though Cheri Beasley, a Black woman running for U.S. Senate in 2022, was at the top of every ballot in the state, fewer than 42% of Black registered voters cast a ballot - the lowest turnout of Black voters since 2010, according to an analysis by the group Democracy North Carolina.

A Marist College poll last month found North Carolina registered voters favoring Trump by 12 percentage points on immigration and nine points on the economy, with 22- and 17-point leads, respectively, with independents. Biden held a five-point advantage on abortion rights and a one-point edge on preserving democracy.

"Mathematically, Biden is in the hunt in North Carolina,' Shumaker said. "Issue-wise, he has a long way to go to win the state."