Washington (CNN) - Arkansas Sen. Blanche Lincoln raised $1.3 million in the first three months of 2010 and has $4.3 million cash on hand, her campaign said Tuesday.
But Lincoln's numbers indicate she has been unable to match the pace set by Lieutenant Gov. Bill Halter, who will face off against Lincoln in the Democratic senatorial primary - now only five weeks away.
While Halter has not released official fundraising totals for the first quarter, he was able to raise $2 million in the month of March alone, campaign spokeswoman Laura Chapin told CNN Tuesday.
Halter's challenge from the left makes Lincoln's already difficult re-election bid even more complicated. Should she defeat Halter in the Democratic primary, she will still face a Republican candidate in the general election.
In the months since Lincoln teamed up with Vice President Joe Biden to launch her re-election bid for a third term, she has faced criticism from labor unions and for what they describe as her move to the right in order to save her seat.
Lincoln has sought to portray herself as a Washington outsider, and in March launched a television ad taking aim at the "bunch of Washington D.C. unions" running ads accusing her of siding with big business over middle class workers.