The board voted to hold a new election , and Harris declined to run in the second go-around, citing his health. Bishop, a state senator from Mecklenburg County, stepped in to replace Harris as the Republican nominee. Bishop gained notoriety in North Carolina following his sponsorship of H.B. 2, the controversial "bathroom bill" that critics say discriminated against transgender people.

The 9th District turned into a hot spot in last year's midterm elections, when Republican Mark Harris beat McCready by a mere 905 votes. However, the state's Board of Elections refused to certify the election results due to allegations that an operative working for Harris' campaign carried out an illegal ballot-harvesting campaign.

Some analysts see the 9th District race as the first election of the 2020 cycle and a possible bellwether of what could come next fall nationwide. The contest between Democrat Dan McCready and Republican Dan Bishop appears tight even in an area President Donald Trump won easily in the 2016 election. Republicans have held the district since 1963.

A U.S. House special election in North Carolina on Tuesday has the potential to serve as an early referendum on the 2020 elections as Democrats seek to upend a stronghold Republicans have held for decades.

Like other special elections since Trump took office, the race has drawn sizable national interest. Trump will try to boost Bishop with a rally in Fayetteville on Monday night. Vice President Mike Pence will aim to boost Bishop on the other side of the district with a speech at Wingate University.

On Monday, Trump tweeted: "North Carolina, vote for Dan Bishop tomorrow. We need him badly in Washington! His opponent is a far left Sanctuary Cities supporter."

While Trump will try to help Bishop across the finish line, the president's popularity has taken a hit in the district since he beat Hillary Clinton by 11 percentage points there in 2016. Currently, he only holds a 47% approval rating, according to an Inside Elections poll, down from the 52% approval he enjoyed in late 2018.

McCready, a former Marine and Iraq War veteran who has campaigned for the past 27 months, has stuck to a playbook that worked for Democrats running in swing districts in the 2018 midterms. He has campaigned on protecting the Affordable Care Act and cutting health costs while steering clear of more liberal positions that some Democrats worry will make it harder to win battleground areas.

Bishop's campaign has tried to link McCready to the more liberal members of the Democratic Party, whom he labeled as "clowns" in a campaign ad in April. Bishop has thrown his weight behind Trump's platform, framing himself as someone who will support the president on gun rights and immigration, including a wall on the southern border.

A recent bipartisan poll from Inside Elections found McCready leading Bishop by a margin of 46% to 42%.

"I think turnout will be very crucial. If you look at the breakdown of how this district is polling, it's largely within the margin of error," said Chelsea Kaufman, assistant professor at Wingate University. "Whoever is turning people out will have more of an edge, especially since special elections have less turnout."

Hurricane Dorian threatened early voting sites in the district. The state Board of Elections limited early voting in three counties on Friday to account for the storm. It extended early voting for an extra day into Saturday after both candidates released statements calling on the board to grant an extension.

The 9th District, which includes the suburbs of both Charlotte and Fayetteville, is itself a microcosm of the American electorate. The median age of the district is just above the median of the rest of the country, and the district's education levels are on par with the rest of the country. About 87% of voters possess at least a high school diploma.

Both parties have spent heavily on the election, shelling out at least $13.8 million combined. McCready's campaign has vastly outspent Bishop's, but Republican outside spending has dwarfed that of Democratic groups.