Sen. Kirsten Gillibrand (D-N.Y.) announced in an email to supporters on Friday that she raised $3 million during the first quarter of 2011.

"Thanks to you, and the generosity of thousands of others just like you, we have given our potential opponents 3 million reasons to understand that a fight for our Senate seat won't be easy," Gillibrand said in the email. "This campaign will be a long and tough road, but we are off to a great start."

A Quinnipiac poll in February found that Gillibrand's favorable numbers are more than double her unfavorables. According to the poll, Gillibrand has 54 percent favorability among New York voters compared to 20 percent unfavorable.

Gillibrand is up for reelection in 2012. She was appointed to the Senate by then-Gov. David Paterson (D) when Hillary Clinton (D) vacated the seat to become secretary of State in 2009.