Both know that with no ads on the airwaves and few Democrats expected to vote, they are taking their time with each of them.
"When it is a low turn-out election, that personal touch, that validation by quality community people means so much," Marshall said.
"And I take those calls," Cunningham said. "And I return them, one on one, to make sure that North Carolinians, Democrats, know what I am all about."
In the May primary, Marshall beat Cunningham by almost 10 points, but still did not gather 40 percent of the vote. The runoff campaign has dragged on for seven extra weeks.
Cunningham has spent almost twice as much money as Marshall, with significant financial help from Democratic Party leaders in Washington.
"We know unseating a tough Republican incumbent in this year requires all the horsepower that our party can bring to bare," Cunningham said. "And they see an opportunity to win with this campaign, and this campaign only."
Marshall has said party-insiders are trying to hand pick a candidate.
"Somebody putting their fingers on the scale to try to take the determination of who's going to be the nominee away from the people of North Carolina," she said. "People think that's wrong."
There are about 2.75 million registered Democrats in the state. But the North Carolina Board of Elections expects turn out Tuesday to come in between 2 percent and 5 percent, which would mean fewer than 150,000 voters, and a cost of $4 million to $5 million to tax payers to hold a state wide election.
The vote on Tuesday will decide who challenges Republican Sen. Richard Burr in November.