"If the Republicans choose to block tax relief for working Americans because they want bonus benefits for the richest — even though that's not a smart investment for America — then I think we need to take that issue to the voters in November," Merkley told reporters.
Whitehouse agreed, saying Democrats "should not yield" to Republicans holding middle-class tax cuts "ransom" so tax breaks for the richest Americans can also continue.
The senators' comments come as rumors persist on Capitol Hill that Democratic leaders might try to extend the middle-class tax cuts before the election and wait to address the upper brackets in the lame duck. Senate Finance Chairman Max Baucus (D-Mont.) said a bill could be introduced as early as next week, according to reports.
Whitehouse said that President Obama is ready to fight Republicans over which tax cuts get extended.
"The president is going to be very active in terms of continuing to fight for the $250,000 differential and for his tax cut plan," the senator said.
Obama has repeatedly said that tax cuts for incomes above $250,000 annually should not continue after this year.
Republicans, and a growing number of Democrats, have argued that all the tax cuts should be extended because of the weak economy.
"They [the White House] are committed to fighting for their program," Whitehouse said.
Both senators expect a vote on the Bush tax cuts before the election.