The National Republican Senatorial Committee had its best fundraising month this election cycle in March, raising $6.35 million.

The haul comes as Republican chances for picking up the six seats they need to win back the majority appear to be looking better. Heavy ad spending by the conservative group Americans For Prosperity has put Democratic senators running in red states on defense early in the election cycle.

"Another record month shows that we are building momentum and that Republicans across the country are highly energized," said NRSC Vice Chairman Rob Portman (R-Ohio), who told his GOP colleagues about the haul at their Tuesday lunch.

The NRSC ended March with nearly $15.9 million in the bank and no debt.

The Democratic Senatorial Campaign Committee has not yet released its March totals. It raised $6.8 million in February and wrapped up the month with $18.1 million in the bank and $1.2 million in debt.