WASHINGTON — The Senate Judiciary Committee considered more than 300 amendments to immigration legislation last month before sending it to the full Senate, which is expected to begin debate on the bill on Tuesday.

But even as they begin a floor fight that is likely to last until the Fourth of July recess, senators from both parties are readying dozens more amendments in an effort to shape the most significant overhaul of the nation’s immigration laws in a generation. Though amendments will continue to roll in during the debate, below are some of the more complicated, controversial and important provisions expected to be offered — including some considered to be “poison pills.”

“RESULTS” Senator John Cornyn, Republican of Texas, has signaled that he plans to introduce a measure that would require several border security triggers — including a 90 percent apprehension rate of illegal crossings — to be met before undocumented immigrants could transition to lawful permanent residence, or green card, status. His amendment also would require putting into place a biometric exit system and a nationwide electronic-verification system, to ensure employers are not hiring workers who are in the country illegally.

Democratic senators in the bipartisan group of eight that drafted the legislation, as well as immigration advocates, seized on the provisions as logistically unfeasible hurdles that could delay indefinitely a path to citizenship for the 11 million undocumented immigrants already in the country. Speaking Sunday on Univision, Senator Harry Reid of Nevada, the majority leader, warned that Mr. Cornyn’s amendment was “a poison pill.”