Updated: 8:22 p.m.

Senate Democrats on Thursday accelerated their push to ratify the new Strategic Arms Reduction Treaty, accusing the Republican opposition of playing politics with national security while vowing to approve START before the Jan. 4 conclusion of the 111th Congress.

The chamber will debate the treaty Friday and Monday, Senate Majority Leader Harry Reid (D-Nev.) said on the floor Thursday night, and it could conclude by the middle of next week. Foreign Relations Chairman John Kerry (D-Mass.) said earlier in the day that all 58 Senators who caucus with the Democrats are prepared to vote to ratify the treaty and that none intends to offer amendments.

Most Republicans, led by Minority Whip Jon Kyl (Ariz.), argue that there is insufficient time to properly consider START, particularly with the treaty splitting floor time with other Democratic priorities. Even Republicans inclined to support START on its merits are threatening to withhold support if Democrats do not kick the debate to early next year.

But Democrats appear to be digging in. Majority Leader Harry Reid (Nev.) repeated his threat to keep the chamber working until Jan. 4 if necessary to complete work on START and other legislative priorities, and Kerry and several other Democrats went before reporters to poke holes in the Republicans’ substantive and procedural arguments for delay.

“Before this Congress ends, we’re going to have a vote on the START treaty,” Reid said during a Thursday afternoon news conference. “The question is not ‘What am I going to do about the START treaty?’ It’s ‘What are the Republicans going to do?’ No one is being jammed.”

Senate Majority Whip Dick Durbin (D-Ill.) and Democratic Sens. Benjamin Cardin (Md.), Bob Casey (Pa.), Chris Coons (Del.) and Jeanne Shaheen (N.H.) held a news conference after Reid’s remarks to press for ratification of START, while Kerry and two Obama administration officials made a similar pitch in a morning session with reporters. Ratification requires the support of two-thirds of Senators present and voting, but it was unclear late Thursday whether resistant Republicans were being swayed in sufficient numbers.

The Senate debate over START began with a yawn Thursday morning, as Members on both sides of the aisle took to the floor to weigh in on the treaty. The GOP is expected to offer several amendments to adjust both the language of the treaty and the document’s preamble, and Democratic leaders begged Republicans to stop stalling and start the process.

Republicans balked, saying they need to lay a rhetorical foundation for amendments that will be offered later. Kyl, the chief Republican negotiator on START, spoke for an hour on the floor explaining his lingering opposition and desire that ratification be pushed to 2011. During a brief interview, Kyl declined to reveal a Whip count but appeared confident that sufficient GOP opposition existed to block ratification of START.

“The more confused and truncated this procedure is, the less likely that they’ll have the votes,” he said.

Sen. Lisa Murkowski voted Wednesday in favor of opening the debate on START. The Alaska Republican warned that the Democrats’ full agenda for the lame-duck session and the possibility of working up to and past Christmas could lead her to vote against ratification. Murkowski also worried that insufficient floor time is available to consider START.

“There’s all these things that everybody wants to do — everybody has to do,” she said. “I want to make sure that we do justice to this treaty.”

If all the Senators who caucus with the Democrats maintain their support for START, nine Republican votes would be needed to achieve ratification. Senate Foreign Relations ranking member Dick Lugar (Ind.) is the only Republican who has announced his full and unconditional support for the treaty.

Sen. Johnny Isakson (R-Ga.) delivered a hearty endorsement of START on the floor Thursday, but his office clarified that he will only vote to support ratification after the government spending bill is addressed. The Senate was scheduled to move to consideration of the omnibus Thursday evening, but with Democrats and Republicans at odds over spending, it remains unknown when the matter will be resolved.

Meanwhile, Sen. Ron Wyden announced that he is having surgery for early-stage prostate cancer Monday and will be recuperating until the 112th Congress convenes Jan. 5. The Oregon Democrat’s absence should not affect the number of Republican votes needed for ratification, however, because only 66 votes will be needed instead of 67.

Democrats spent much of Thursday attempting to undercut GOP arguments for pushing START to next year.

To claims that GOP Senators-elect should have an opportunity to vote on ratification, Democrats said that would only lead to requests for further delays so that the 2011 freshman class could get up to speed. To claims that the lame duck allowed inadequate time to consider START, Democrats said Republicans have had a year to review treaty negotiations and the completed document.

Democrats also said Republicans’ substantive problems with START were unfounded. Democrats pointed to a host of former Republican officials who support START, including ex-diplomats and secretaries of state. Casey even tried to tie ratification of START to the struggling economy, saying that during a time of such financial insecurity, progress on a key foreign policy matter would give Americans a much-needed emotional boost.

“Ratification of this treaty would give people some peace of mind,” the Pennsylvania Democrat said.