The Washington Post Election Lab's Senate forecast model is far more optimistic about North Carolina Sen. Kay Hagan's chances for reelection than its competitors. While Election Lab rates that there is a 78 percent chance Hagan will win, both Five Thirty Eight and the New York Times' Upshot have left the race a 50-50.

Sen. Kay Hagan, D-N.C. (AP Photo/Gerry Broome, File)

Why does our model think Hagan's got a good chance of winning despite the doomsday predictions about the Democrat's chances coming from all angles? This early in the race, before the money and ads and unforeseen national events take their toll, the fundamentals are in her favor. First, she's an incumbent. Second, she has a considerable fundraising advantage over Thom Tillis, the North Carolina state House speaker who won the GOP Senate nomination on Tuesday. While Tillis has slightly less than $1 million in the bank after his primary, Hagan has raised about $8.6 million. Third, state legislators don't have the best track record when it comes to beating incumbents. Ben Highton, one of the three people who built the Election Lab Senate forecast, crunched the numbers, and only six state legislators have beaten incumbent U.S. senators since 1980.

Eighty-six state legislators have been in Tillis' position. And only six have managed to make it work.

Interestingly enough, Hagan was one of them. In 2008, state Sen. Kay Hagan — whose only familiarity with the U.S. Senate was operating a Capitol elevator as an intern in the '70s — ran against incumbent North Carolina Sen. Elizabeth Dole. No one thought she could win, and the polling wasn't very favorable to an upset either. Until two months before the election, that is, when Hagan took the lead and kept it. Dole ran a bad campaign, and the Democratic Senatorial Campaign Committee devoted more resources in North Carolina than they did in any other state. The Obama campaign, which invaded the state with volunteers in a successful attempt to turn the red state in their favor, likely helped the fellow Democrat further down the ticket too. It may have been an improbable victory, but it was a beautifully executed one.

Two state legislative leaders — similar to Tillis in that regard — are also among the lonely six victors. Montana Sen. Jon Tester — a former president of the Montana state Senate — beat Conrad Burns in 2006 by 0.87 percent. In 2008 — a good year for Democratic state legislators all around, given that a former state senator topped the presidential ticket — Jeff Merkley, speaker of the Oregon state House, beat the Republican incumbent Sen. Gordon Smith. And why, you might ask, is Obama not in our list of ascendant state senators who became senators? The race he won was an open one. It's not as difficult to graduate from state to federal politics when your opponent is as much of an unknown as yourself.

The three other state legislators beat incumbents in the '80s and '90s. Republican state Sen. Peter Fitzgerald beat Illinois Sen. Carol Moseley-Braun — the first black woman to be elected to the Senate — in 1998. In 1992, Republican Sen. Bob Kasten lost to Wisconsin state Sen. Russell Feingold. Nevada state Sen. Chic Hecht beat Democratic Sen. Howard Cannon in 1982.

What do these six state legislators reveal about the North Carolina Senate race? First, it's far too early to write off either candidate. With more than five months to go until Election Day, the election could change in myriad ways. While the Washington Post election model has Kay Hagan as a "buy" right now, John Sides, who helped build the model, told the Fix earlier this week, "the current model is based only on conditions today.  If conditions change or the polls shift because of unexpected events in a race, our forecasts will change too." Outside groups are sure to funnel millions into the race against Hagan; Americans for Prosperity has already spent more than $7 million against her before the general election began. The Democratic Senatorial Campaign Committee is looking to make a repeat performance in the state too, investing in voter registration and outreach. If the economy goes south, or the Obama administration suffers a major blow, that would likely tilt the race in Tillis' favor.

The national frame of the 2014 midterms bestows great favor on Republicans, and if Tillis plays this right, he could join the 7 percent of state legislators who beat incumbent senators.

However, the fact that only 7 percent of Tillis-like challengers have won goes a long way toward explaining why Hagan's chances of reelection are at 78 percent. The race is young, and history is in her favor.