Harkin said he objected to the extension of tax breaks to those making more than $450,000 a year.
Before the Senate even voted on the "fiscal cliff" bill, Iowa Senator Tom Harkin blasted the bill, calling it a "compromise I simply cannot support."
In a statement, Harkin said he objected to the extension of tax breaks to those making more than $450,000 a year.
President Obama had initially wanted to raise taxes on those making more than $250,000 a year.
"In essence," Harkin said, "this agreement locks in a tax structure that is grossly unfair to middle class Americans, one which provides permanent tax assistance to wealthy Americans, and only temporary relief to everyone else."
Senator Chuck Grassley, of Iowa, also voted "no".
The Republican called it a "fiscal farce" to raise taxes, and hurt economic growth, only to fuel more government spending with record deficits and debt.
Senator Mike Johanns, of Nebraska, reluctantly voted for the bill.
The Republican said "the agreement isn't my ideal option, but I firmly believe going over the cliff isn't an option at all,"