WASHINGTON (AP) — Senators finalizing a massive immigration bill are arguing over plans to boost visas for high-tech workers, Senate aides and industry officials say, with disputes flaring over how best to punish companies that train workers here only to ship them overseas.

Sen. Dick Durbin, D-Ill., who's taken the lead in pushing to crack down on outsourcing firms, also is seeking higher wages for workers brought in on the H-1B visas that go to specially skilled foreigners, aides and officials say. High-tech industry officials say his efforts risk punishing companies not involved in the abuses he's trying to target, and lawmakers including Sen. Marco Rubio, R-Fla., are taking the other side.

The dispute comes as aides to four Democratic and four Republican senators have been racing to put the finishing touches on sweeping immigration legislation that would secure the border and grant eventual citizenship to 11 million people here illegally, while also allowing tens of thousands more high- and low-skilled workers into the country on new visa programs.

Aides worked into the evening Monday on the high-tech visa issue, and senators were to resume meeting in person Tuesday after returning to Washington from a two-week spring recess. They were hoping to complete their legislation this week, though next week may be looking more likely. The high-tech visa question loomed as one of a few remaining unsettled matters.

At issue is overwhelming demand from companies like Microsoft, Apple and Google for the H-1B visas, which are now capped at 65,000 annually, plus 20,000 more that are reserved for foreign workers who have earned an advanced degree from a U.S. university. On Friday, the Homeland Security Department announced that after less than a week of accepting applications, it already had received more requests than visas available for the 2014 budget year.

Faced with that demand, senators have contemplated lifting the cap to around 100,000, with the ability to go as high as 150,000, aides and officials said. They spoke on condition of anonymity because negotiations were ongoing, and they stressed the numbers remained in flux and no final decisions had been made.

Such an increase would be a win for the tech industry, which has boosted its lobbying muscle in Washington in recent years. On a related issue, the legislation also is likely to allow permanent U.S. residency to unlimited numbers of people who get advanced degrees in science, technology or math from U.S. universities.

But the proposal to increase H-1B visas is focusing attention on problems with the current system.

Daniel Costa, immigration policy analyst at the Economic Policy Institute, a left-leaning think tank, said the top 10 companies with the most H-1B visas last year were all firms that bring workers here to work at lower cost than Americans would, then send them back home. Many are technology companies based in India.

"There need to be some major reforms before expansion happens," Costa said.

Senate negotiators have discussed fees and other penalties for companies that use large numbers of H-1B workers, including requiring those with more than 30 percent of their workforce made up of H-1B workers to pay higher wages than others, and those with more than 50 percent of H-1B workers to pay higher wages still. There would potentially be a prohibition against a company hiring more than 75 percent of its workers on H-1B visas. No such limit exists in current law.

But Durbin has been pushing to block companies from hiring any more than 50 percent of their workers on H-1B visas, aides and officials said. More problematically for U.S. firms, he also is pushing for higher wages, which industry officials contend could result in H-1B workers getting paid more than their American counterparts. And he's sought to push companies to make greater efforts to hire American workers first.

"Sen. Durbin has advocated for meaningful reforms of the H-1B visa program for years, and that hasn't changed in these negotiations," Durbin spokesman Max Gleischman said late Monday. "Any discussion of raising H-1B caps must also include protections for American workers and safeguards to ensure American jobs aren't being shipped overseas."

Scott Corley, executive director of Compete America, which represents high-tech companies including Google, Intel and Microsoft, said companies that are not heavily dependent on the H-1B visas shouldn't be subject to some of the new restrictions Durbin has advocated.

"If you believe these visas are somehow being exploited, who is more likely to exploit them?" Corley said. "There are tons and tons of people who apply for one or two of these visas every year, so you have to step back and say do we want to do this in a judicious way."