Senate Majority PAC raised $11 million in the first three months of 2014, a major haul for Democrats' main Senate super-PAC.

That's a huge jump from two years ago, when the group raised just $1.7 million in the first quarter of 2012.

The group has raised just shy of $20 million for the election cycle and has $8.5 million left in the bank after going on the air to defend a number of Senate Democrats this year and their fragile six-seat majority. 

Senate Majority PAC is Democrats' first line of defense against big-spending GOP groups. But the other side still has the edge — Americans for Prosperity alone has already spent more than $30 million in this election cycle and will likely continue to outpace Democrats with its spending.