About halfway through the midterm election cycle, North Carolina is on pace to host the most expensive Senate race of 2014.

But the Tar Heel State shouldn’t necessarily get too comfortable in the top spot.

Democratic Sen. Kay Hagan’s re-election battle is one of at least four Senate contests where outside spending has already eclipsed the $2 million mark. The others include the re-election races of Sens. Mark Pryor, D-Ark., Mary L. Landrieu, D-La., and Mitch McConnell, R-Ky.

The potential for Republicans to win back the Senate majority, combined with the media-market makeup of the competitive landscape, has invited a superfluity of early spending. Republicans need a net gain of six seats next year, and most of the competitive races are for Democrat-held seats in less populous states.

“Given the president’s plummeting job approval ratings, there is growing optimism that Republicans can win back the Senate, and that’s why you’re seeing some very early spending in key U.S. Senate races,” GOP media consultant Erik Potholm said. “And Democrats, especially their vulnerable incumbents, are feeling that same pressure — that’s why Sens. Landrieu and Pryor are on the air.”

The major players in outside spending so far have been Americans for Prosperity, a GOP-aligned group underwritten by the Koch brothers, and Senate Majority PAC, whose primary goal is to keep Democrats in the majority. Both groups were also highly active in the 2012 elections and were able to ramp up their spending operations early this cycle.

North Carolina has some of the largest and most expensive markets of any top Senate race states this cycle. And given the competitiveness of Hagan’s re-election bid, the early spending figures reflect that.

According to media buying figures obtained by CQ Roll Call, Republican outside groups have outspent their Democratic counterparts in North Carolina, $5.7 million to $2.6 million. That includes the $750,000 airtime purchase in early December by Senate Majority PAC and about a $4 million total investment from Americans for Prosperity.

The numbers are based on information provided by media consultants in both parties as of Dec. 10. Not all of the money was spent as independent expenditures, which must be filed to the Federal Election Commission, so exact figures were not available.

Compared with North Carolina, the spending discrepancy between the two parties is closer in other states. Democrats hope to keep pace with the GOP outside groups targeting their incumbents, as well as define Republican challengers before they can define themselves.

Senate Majority PAC Campaign Director Ty Matsdorf said the group is attempting to highlight GOP challengers — specifically North Carolina state Speaker Thom Tillis and Reps. Bill Cassidy of Louisiana and Tom Cotton of Arkansas — who advocate “irresponsible and dangerous policies.”