The bipartisan immigration proposal is making its way through the Senate Judiciary Committee.
On Tuesday night, Senators added 300 amendments to the bill, and on Thursday both parties are going head-to-head to see which of these additions will help the bill's passage in Congress.
Immigration reform is a top priority for both parties, but the subject of security is a sticking point for Republicans.
What’s at stake: the Gang of Eight’s delicate compromise forged after months of internal debate
The committee session is expected to last two weeks.
Update at 10:09 a.m. PDT:
The committee voted 12-6 to strike down a high profile amendment to the immigration reform proposal it is now hearing.
Republican Charles Grassley wanted the entire border with Mexico to be brought under operational control before starting a path to citizenship. The bill only calls for the three Border Patrol busiest sectors to be brought up to 90 percent control. Grassley warned the committee.
"If we don’t make this very clear, we can have situations where 10 years down the road, we don’t have effective control," he said.
The vote fell along party lines. The committee also voted to approve a segment of the bill that would have established border crossing fees.
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