In 2010, Sen. Richard Burr did what no other U.S. Senate candidate has done in North Carolina in the last 25 years – win by double digits.

As he goes for a third term in 2016, the Winston-Salem Republican would seem to be in an enviable position.

He has a war chest of nearly $4 million. No Democratic opponent. And recent polling numbers – by a Democratic-leaning firm no less – that showed him with solid leads over a half-dozen possible rivals.

But there are at least three reasons Republicans might not want to get over confident.

1. The field isn’t set

The person who might have been Burr’s strongest challenger, former Sen. Kay Hagan, said last month she won’t run.

Even before, a lot of big-name Democrats, including U.S. Transportation Secretary Anthony Foxx and state Treasurer Janet Cowell, had taken themselves out of the running. Others have since said no, though some closed the door tighter than others. But it’s early.

In the summer of 2007 some of the same Democrats whose names pop up now were passing on a race against Republican Sen. Elizabeth Dole, who looked strong. That October even Hagan bowed out of consideration. Two weeks later she changed her mind, jumped in and went on to win.

That Burr has no challenger now doesn’t preclude one, even a strong one, for 2016. Could Hagan change her mind again? “I doubt that,” she told me.

2. It’s a new playing field

That Burr has a fundraising edge may not matter. The rules have changed.

Since the Supreme Court’s 2010 Citizens United decision, big-money donors have had a growing influence on elections through super PACs and 501(c) groups.

Last year, outside groups spent nearly $83 million on the race between Hagan and Republican Thom Tillis. That helped make North Carolina’s $118 million race the nation’s most expensive, and helped Tillis overcome Hagan’s 2-1 edge in fundraising.

With Democrats needing five seats to regain control of the Senate (four if there’s another Democratic president), North Carolina will surely be in their sites again. No matter how much Burr raises.

“If you know that there’s a super PAC coming in, that (fundraising) difference doesn’t mean anything anymore,” says Jennifer Duffy of the Cook Political Report.

3. It’s a purple state

From 1980 to 2008, it was good to be a North Carolina Republican running for the Senate in a presidential election year. Then came President Barack Obama, who carried the state and helped lift Hagan to victory.

Democrats who have watched their turnout drop in off-year elections have seen it spike in presidential years. That’s not expected to change in a year when Hillary Clinton is expected to top the ticket and one that also features a hotly contested governor’s race.

It’s become a deeply purple state. Nowhere did Obama win more narrowly in 2008 or lose more narrowly in 2012.

A recent study found that over the last quarter-century no state had more competitive Senate races than North Carolina. Odds are the 2016 race will revert to form.