U.S. Sen. Daniel Akaka of Hawaii has signed a letter with at least seven other senators urging a vote on an alternate tax cut proposal that would repeal Bush-era tax cuts for people earning more than $1 million a year.

The Democrats on Friday said their proposal would dedicate the resulting revenues to the Social Security trust fund.

The letter says a compromise brokered by President Barack Obama and congressional Republicans contains provisions they support.

But it says the accord also includes a "deeply misguided allocation of resources" that the U.S. cannot afford.

The senators propose to extend current tax rates to everyone but millionaires, whose rates would revert to higher Clinton-era levels.