Efforts in the U.S. Senate to approve a major reform of U.S. immigration law are on the brink of failure amid disagreements between majority Democrats and Republicans over its provisions. VOA's Dan Robinson reports from Capitol Hill.

Legislation to overhaul what most assert is a broken immigration system and provide an estimated 12 million illegal immigrants a path to U.S. citizenship has been the subject of heated debate since the plan was unveiled by a bipartisan group of senators a few weeks ago.

Supporters, including President Bush, have argued that, in offering the most sweeping changes in two decades, it would mark an important step toward fixing many of the immigration problems.

They argue that the bill stops short of declaring an amnesty for illegal immigrants, while offering a guest worker program, taking steps to strengthen border security and help immigrants and their families as well as American employers.

But opponents argue that the bill is flawed and does not do enough to enforce security at U.S. borders.

On Thursday, the Senate defeated attempts by Democratic majority leader Harry Reid to shut down debate, which would have cleared the way for a vote.

Senator Reid warned that failure to pass the bill would mark the end of any realistic hope for immigration reform while President Bush is in office. "If this bill goes down with the vast majority of the Democrats voting for this action to move forward on this, and the Republicans vote against it, he and I discussed what the headline is going to be, and the headline is going to be: Democrats vote to continue the bill, Republicans vote against it, the president fails again," he said.

Reid acknowledged frustration that the process was being slowed by numerous amendments from both sides of the political aisle. But he says Republicans were principally to blame for blocking progress.

Senator John Ensign, a Nevada Republican, was among those arguing that the legislation was being pushed too fast by Democrats. "It is too important a piece of legislation to rush it through here, to say that we want to do other things [and] we have other priorities. Well, right now I don't think the American people think that there is too much more of a priority than fixing our immigration system. It literally is broken, and we have to design an immigration system that is good for America," he said.

"They are not going to buy into a bill that is not going to work. They expect us this time to do something that works," said Republican Jeff Sessions.

In earlier debate on the legislation, the main backers of the bill suffered a defeat when the Senate approved an amendment, proposed by a Democrat, to place a five year limit on a new temporary guest worker program the legislation would create.

Despite the opposition, majority leader Reid scheduled another vote on ending debate for later Thursday. If that fails, chances for immigration reform will have suffered a major setback. "We need to have the record reflect that this bill isn't going anyplace but it is not our fault. I repeat, this is a bill that was negotiated in good faith by Democrats and Republicans, and it is the president's bill he says he wants this," he said.

Reid suggests that President Bush needs to become personally involved again if there is to be any chance of salvaging immigration reform at this stage.