Sen. Kay Hagan (D-N.C.) was a very productive fundraiser during the first three months of 2014, bringing in nearly $2.8 million, her campaign announced. Hagan's total is more than double the haul of the leading Republican running against her, state House Speaker Thom Tillis.

Tillis raised $1.3 million during the first quarter, his campaign confirmed Monday. He ended March with $1.3 million in the bank, far less than Hagan's $8.3 million cash stockpile.

While the vulnerable Democratic incumbent has been a steady fundraiser, Republicans have dominated the air war in North Carolina. They have been blanketing the airwaves with commercials hammering the first-term Democrat, hurting her poll numbers.

Overall Republican ad spending more than doubled Democratic spending through late-March, according to Democrats' tally. The biggest spender has been Americans For Prosperity, a conservative group backed by the billionaire industrialist Koch brothers. AFP spent about $7 million on advertising against Hagan through the end of last month.

The Fix recently rated North Carolina as the sixth most likely Senate race to flip party control this year. Republicans need to pick up six seats to win the majority.

The Wall Street Journal first reported Tillis's first quarter numbers.