Tighter US borders?

After years of stop-and-go travel, the effort to rewrite United States immigration laws is rolling down the express lane. The bitter and emotion-laden opposition of Hispanics and their allies has failed to halt the reform in the face of a broad national consensus for reducing the influx of illegal aliens.

''I think it will pass,'' said a weary Rep. Robert Garcia, head of the Congressional Hispanic Caucus, during a break from the House debate this week. The New York Democrat's impassioned charges that the legislation will discriminate against anyone who looks or sounds foreign did not convince the House of Representatives. The provision that imposes sanctions against employers who hire illegal aliens won by almost a 3-to-1 margin.

''We've kept it off the (House) floor for a good three or four years,'' said Representative Garcia of the reform bill cosponsored by Rep. Romano L. Mazzoli (D) of Kentucky and Sen. Alan K. Simpson (R) of Wyoming.

''The time has come,'' the New Yorker conceded.

The Senate has twice passed a similar version of the Simpson-Mazzoli bill, but until this week the legislation has bogged down in disputes and troubling amendments in the House. But early this week, the House agreed to take up the issue again, and the first vote signaled a change of spirit and a new determination to dispose of the immigration issue.

In that procedural vote, the House moved 291 to 111 to bring up the bill for debate. Opponents had hoped to nip the bill in the bud and used their emotional ammunition during that first battle. However, that tactic backfired. Republicans answered by showing united support for the bill, removing the fears of Democrats that the issue may be an election-year political trap.

Since that test vote, the supporters have steered the bill steadily through the proposed amendments.

''I kept saying there was a broad constituency'' for reform, says Representative Mazzoli in an interview. The members ''realize it isn't a mine field,'' says the Kentuckian, who points out that since then ''each vote is more resounding and decisive.''

''We've taken the wind out of the sails of those who wanted to scuttle the bill,'' says Rep. Dan Lungren (R) of California, who is leading the fight on the GOP side.

One of those opponents, Rep. Bill Richardson (D) of New Mexico, says his side has been taken by surprise. ''There's a very strong mood to have some form of immigration reform. The members feel they've got to do something,'' he says.

So far the House version of the reform has retained its principal features, and supporters have warded off major changes. The main enforcement tool in both House and Senate versions would be employer sanctions. At present, employers are not barred from hiring undocumented aliens.

Under the bill, employers would be fined nothing for a first offense, $1,000 for a second offense, and thereafter $2,000 for each illegal worker. The House has removed provisions for bringing criminal charges against employers, which are included in the Senate version. But it is widely believed the final law will be closer to the Senate language.

The biggest controversy is whether to include the amnesty provisions for certain illegal residents. There are now between 2 and 10 million undocumented aliens, and an undetermined number would be eligible for legalization. The House bill would grant legal status to people living here since January 1982. The Senate version, passed last year, has a more modest plan, granting legalized status to those here before 1977 and temporary status to those here since 1980.

But in the House, opposition to amnesty has grown so strong that some supporters fear the provision could be wiped out entirely.

''They won't do away with it,'' predicts Mazzoli, but he says the House will tighten up the amnesty provisions.

Even Hispanic Caucus member Richardson says he prefers tougher amnesty provisions. ''I am concerned about protecting American jobs,'' he says, explaining that many of his Hispanic constituents are ''leery about amnesty,'' which they equate with granting citizenship.

Mazzoli predicts that when the House takes up legalization, today or early next week, it ''will survive by a few votes.'' If all the amnesty provisions are dropped, the bill would be in danger, its supporters say. But Mazzoli says even if the House stripped out amnesty, Senator Simpson could probably reinstate it in a joint House-Senate conference on the bill.