Sen. Jim DeMint (R-S.C.) urged his GOP Senate colleagues Friday to reject a deal on the extension of Bush-era tax cuts and wait until the incoming crop of GOP senators are sworn in to move forward.

In an e-mail to supporters of his Senate Conservatives Fund, DeMint said waiting until the January arrival of many of the Senate Republicans, whom he helped elect this past cycle, would mean the GOP could "fight for a better deal."

"I appreciate the efforts made by my party's leaders to negotiate this deal but I believe Americans deserve much better. This deal should be rejected and then fixed," DeMint wrote. "We can easily extend these tax rates without increasing spending once the new crop of Republican senators, including Pat Toomey, Marco Rubio, Rand Paul, Mike Lee and Ron Johnson are sworn in."

DeMint's Senate Conservatives Fund endorsed and offered fundraising help to all five of those newly elected GOP senators in 2010.

"The president has already conceded that taxes cannot go up and we'll have more Republicans in Congress in a few weeks to fight for a better deal," DeMint concluded.

The South Carolina Republican announced earlier this week that he wouldn't back a compromise extending Bush-era tax cuts across the board and extending unemployment benefits, saying the package adds too much to the budget deficit.

Senate Democrats are moving ahead with the deal while adding some sweeteners in an attempt to convince House Democrats to go along. Reid has added an ethanol tax credit and an extension of the Section 1603 cash grant program for the renewable energy industry--additions targeting Sens. Tom Harkin (D-Iowa) and Sherrod Brown (D-Ohio). 

A GOP Senate aide points out that the additional tax provisions are nothing new, simply extensions of current tax policy. 

Senate Majority Leader Harry Reid (D-Nev.) scheduled the first Senate vote on the plan for Monday.

-Updated at 1:45 p.m.