Senate leaders breathed new life Thursday night into stalled immigration legislation, announcing they would bring the bill back to the floor but making no promises about the substance of the legislation.

Majority Leader Harry Reid, D-Nev., and Minority Leader Mitch McConnell, R-Ky., made only a vague commitment, saying in a statement that “the immigration bill will return to the Senate floor after completion of the energy bill.”

That means the bill would probably be on the floor no earlier than late next week and probably not until the week after.

While senators in both parties expressed optimism that the agreement meant the bill is headed toward passage, conservatives who played a role in derailing the bill last week were left out of the latest deal-making.

“We’re standing in front of a train, there’s no doubt about it,” said Jim DeMint, R-S.C., a leader of the group of Republicans trying to kill the bill.

The breakthrough came hours after President Bush called for $4.4 billion in border security spending to be added to the bill — an effort to win over those who want to enforce current laws before providing a path to legalization for illegal immigrants.

DeMint said Bush’s proposal “may give enough people cover to vote for the bill.”

The first step when the bill returns to the Senate floor will be a fourth vote to invoke cloture, which would limit debate on the legislation and cut off a filibuster. Leaders from both parties are confident that they will reach the 60-vote threshold after coming up short in three attempts last week.

“I think we can get cloture,” said Minority Whip Trent Lott, R-Miss., whose job is to count Republican votes. “I’m already working it.”

If the cloture vote is successful, next in line would probably be an amendment by Republicans Mel Martinez of Florida, Jon Kyl of Arizona and Lindsey Graham of South Carolina that would provide $4.4 billion in mandatory spending on border security in interior enforcement. That was the essence of the plan Bush backed Thursday, and top Democrats also embraced the idea.

Members said that under the agreement, each party is likely to be limited to about 10 amendments, and the bill could be wrapped up in a matter of days once it is brought back to the floor.

Proponents of the bill have been engaged in a delicate negotiation regarding which amendments to consider, trying to ensure that each side is satisfied that its voices are heard while also guaranteeing that nothing that would wreck the compromise can attract enough votes to get attached to the bill.

One of the most contentious amendments, by Kay Bailey Hutchison, R-Texas, would require illegal immigrants to return to their home countries before they can apply for legal status, a process known as “touchback.” It’s not clear whether Democratic negotiators have agreed to allow a vote on that proposal, which is vehemently opposed by immigration advocates.

The final drive toward agreement began June 12, when Bush met with a skeptical Senate Republican Conference and heard from members that they feared that even if the bill included stronger border security and interior enforcement, that was no guarantee that the money for it would be appropriated or that the agencies would be able to carry it out. They needed to see something more concrete, they told the president.

Martinez, a GOP negotiator, said the proposal for mandatory border security spending that grew out of that meeting “gave a lift” to the negotiations.

A spokesman for McConnell added that “it’s a step in the direction of where people want to be.”

The $4.4 billion would be added to the legislation as mandatory, upfront spending for border security and enforcement. Inserting such a provision into the bill would require 60 votes for the Senate to waive budget rules.

Some Republicans expressed a preference for providing the money in a separate, emergency supplemental appropriations bill.

Johnny Isakson of Georgia, a conservative who has been targeted as one Republican who might back the legislation if it has the right border security elements, said he supported the idea of “decoupling” money for border enforcement by way of a supplemental spending bill, with the path to legalization and a guest worker program being dealt with separately.

But Isakson was not ready to commit to creating a mandatory spending program in the immigration bill itself.

One hotly debated provision likely to remain untouched is an amendment, adopted June 7, that would sunset the bill’s Y-1 non-immigrant temporary worker visa program after five years. Some bill proponents want to remove that provision, but Martinez said it is likely to remain and not be subject to further amendment.

That, however, could change in conference committee.

Kathleen Hunter contributed to this story.

First posted June 14, 2007 2:06 p.m.