Sen. Debbie Stabenow raised $1.5 million in the first quarter of this year — a sum her campaign called her "best fundraising quarter ever."
The Michigan Democrat banked about $7 million by the end of March for her race against the likely GOP nominee, former Rep. Pete Hoekstra.
Stabenow faced the first tough re-election challenge of her career at the start of the 2012 cycle. But Hoekstra stumbled earlier this year when his campaign released a controversial Super Bowl spot that even Republicans criticized for its racial overtones.
Stabenow spokesman Nate Byer hinted the spot helped drive the influx of cash.
"When Hoekstra and out-of-state interest groups launched ridiculous negative attacks, people in Michigan responded forcefully with an outpouring of support that gave Debbie her best fundraising quarter ever," Byer said in a statement.
A representative from the Hoekstra campaign said its fundraising totals were not ready yet.
Roll Call rates the Michigan Senate race as Likely Democratic.