Estimates in mid-September indicated that 43 percent of Republican candidate Elizabeth Dole's individual contributions came from donors outside North Carolina, according to the online campaign finance database Political Money Line. Thirty-three percent of Bowles' individual contributions are from outside the state.
More recent reports from The Charlotte Observer place Dole's individual out-of-state contributions as high as 57 percent.
"It's definitely representative of the fact that these are two campaigns truly national in scope," said Ferrel Guillory, director of UNC's Program on Southern Politics, Media and Public Life.
Pat Sellers, political science professor at Davidson College, said the amount of outside money raised by the two candidates is definitely high compared to other Senate races.
"It makes sense, though, because a one-seat switch could mean a change in power," he said. "This is a very important race."
During much of the last session, Democrats controlled the U.S. Senate 50-49, with one Independent who typically voted Democratic.
A loss of one seat by the Democrats would give control of the Senate to the Republicans, possibly handing them control of not only the executive branch but also both chambers of Congress.
"The more competitive the race, the higher the stakes, and the more national money is going to come in," Sellers said.
Since the beginning of the 2002 election cycle, Dole has raised more than $12 million, $9.8 million of which comes from individual contributors. Bowles' numbers are slightly lower -- $9.8 million, $4.8 million of which comes from individuals.