Washington (CNN) - Procedural maneuvering bogged down action in the Senate Wednesday on the first full day of debate on the immigration reform bill. Senators discussed key amendments but battled over whether and how to cast votes so early in the debate.
At one point, Senate Majority Leader Harry Reid pushed for a series of quick votes on Republican amendments, including two significant measures to tighten border security requirements in the bill. But Republicans objected to Democrats' demand that a supermajority of 60 votes be required for passage.
Strategically Republicans knew they would lose leverage if their amendments were to fall early in the debate. They offered to hold the votes at a more favorable 50-vote threshold but Democrats objected to that idea, worried that under that scenario some of the GOP amendments might pass.
Sen. Charles Grassley, R-Iowa, an opponent of the bill, called Reid's move "provocative" and said if a 60-vote threshold is required "it really looks like the fix is in and the bill's rigged to pass basically as it is."
Reid countered that Republicans for years have demanded a 60-vote threshold for the most important measures before the body.
Sen. Jeff Sessions, R-Alabama, a leading critic of the bill, also complained that, "We can't just throw up a bunch of amendments here at the beginning and people haven't had time to digest them."
The two key border security amendments were offered by Grassley and Sen. John Cornyn, R-Texas, the number two GOP leader. Cornyn's amendment would require the government to stop 90% of illegal border crossings before other reforms related to a pathway for citizenship for undocumented immigrants in the U.S. would kick in.
Reid has called Cornyn's requirements unachievable and his amendment a "poison pill' designed to kill the bill.
Nevertheless, toughening the border security provisions in the bill is seen by senators in both parties as the key to its passage. Cornyn's amendment picked up support Wednesday from Sen. Mark Kirk, a moderate Republican from Illinois, who said he would vote against the bill final bill unless Cornyn's amendment, or something close to it, is included.