A showdown on comprehensive immigration reform is set for next week as Senate Majority Leader Harry Reid announced Wednesday that in the face of Republican filibuster threats he intends to bring to the floor the now unpopular bill that passed the Senate last year.

"Everyone has known for months the timeframe that we have in the Senate to do this. We have two weeks set aside," Reid, D-Nev., said, adding that he was using the measure merely as a placeholder for a bipartisan bill if one could be reached. Reid said he would permit "an open amendment process."

Republicans who have been involved in backroom meetings with Democrats and White House negotiators skeptical of Reid's motives said they see the majority leader's move as a hostile one that could very well torpedo an intense, monthslong effort to design a compromise.

Chief Republican negotiators Sens. Arlen Specter of Pennsylvania, John McCain of Arizona, Lindsey Graham of South Carolina and Mel Martinez of Florida sent a letter to Reid warning that they would "only support moving forward with legislation that is a product" of the current bipartisan effort.

The Bush administration is also interested in a new bill. Homeland Security Secretary Michael Chertoff and Commerce Secretary Carlos Gutierrez began meeting with interested Republicans senators months ago at the request of Republican Conference Chairman Sen Jon Kyl of Arizona.

Those negotiators agreed that the bill passed last year, authored by Democratic Sen. Ted Kennedy of Massachusetts as well as McCain, Specter, and Martinez is dead in the water this time around. Gone now are provisions for unlimited family migration, a special path to citizenship for the 12 million illegals in the United States and an acknowledgment that merit needs to play a more prominent role in the doling out of work visas for a temporary guest worker program.

The group then began to meet with Democrats Kennedy, along with Judiciary Committee Chairman Patrick Leahy of Vermont and Sens. Ken Salazar of Colorado and Robert Menendez of New Jersey to try to find common ground. Meetings were intense at times, and at one point, according to aides, both sides walked away in disgust.

Martinez said Wednesday the bipartisan group has broad agreement on "a structure of a bill that would work." Aides involved in the negotiations told FOX News that the outlines include a border security-related trigger that would bar undocumented immigrants from obtaining legal status until the administration is able to "beef up the borders" and implement a tamper-proof, biometric identification system for all guest workers, along with strict employer sanctions for employing illegal workers.

The backlog of immigrants seeking citizenship, according to the aides, would also have to be cleared before the current 12 million illegals could be considered, a key for Republicans to avoid the politically untenable "amnesty" label that critics of the plan used last year in reference to the Senate-passed bill.

"The negotiations that we have been involved in for a long time are tough. And, as Senator Kennedy said, we are not there yet. There's still a long ways to go," Salazar said Wednesday.

Negotiators on both sides said that the next 24 hours are crucial toward reaching a compromise. Reid, so far, shows no signs of allowing the negotiators more time. The negotiators show no real sign they can produce a concrete work product.

Bush has made immigration reform a top priority in his administration, but Leahy said, "The president has got to be personally involved. He cannot just send up Cabinet members and ask them to speak with a few members of the president's party and think that that's going to get you through. You cannot issue great-sounding press releases on a take it or leave it basis. ... This won't work unless he comes in and talks to both Republicans and Democrats, and makes it very clear that he is behind our efforts."