Sen. John McCain (R-Ariz.) today filed an amendment on the looming across-the-board defense cuts on behalf of Armed Services Committee Republicans, and the proposal could prove to be the first test on a sweeping farm bill scheduled to hit the floor this week.

The McCain amendment, which would require Defense Secretary Leon Panetta to file a detailed report by Aug. 15 on the security effects of the nearly $500 billion defense sequester, was discussed at length by the entire Senate GOP Conference at a weekly steering committee lunch this afternoon.

“Congress needs an official, detailed assessment from the Department on the serious damage to military readiness and the increased risk to our military operations in Afghanistan which would result if sequestration is allowed to occur due to the inability of the Administration and Congress to enact an alternative deficit reduction plan,” McCain said in a statement. “We cannot wait until after the election to act.” The sequester was triggered by the failure of the super committee to reach a deficit reduction deal. As a result, $1.2 trillion in automatic cuts to defense and domestic programs are set to begin taking effect in January.

Though the push to reverse the defense part of the sequester is especially popular among Republicans, the move to attach the McCain measure to a delicately negotiated, $969 billion bipartisan farm bill could be just the first of many to threaten final passage.

Senate Agriculture Chairwoman Debbie Stabenow (D-Mich.) and ranking member Pat Roberts (R-Kan.) worked aggressively to pass the bill out of their committee, appending dozens of amendments to the panel’s final product and approving the five-year authorization bill on a 16-5 vote.

But the amendment jungle on the Senate floor is much trickier. In a press conference today, Stabenow and Roberts admitted the process will not be easy. They re-emphasized their open-door policy for Members and their tempered confidence the legislation can pass quickly. They also know, however, that the fate of their bill may depend in part on Senate leaders who often have tried to score political points this Congress at the expense of legislating.

“In regard to Sen. McCain’s amendment, I think it has merit. I would prefer it that all nongermane amendments to agriculture be considered in a separate venue, but then again I know that’s not possible,” Roberts said. “So we are opening the door, like Bob Barker, ‘Come on down.’ Talk to us. We will try to accommodate anybody and everybody on any section of the bill to try to improve it. The chairwoman has worked diligently in that regard.”

Roberts said that he and Stabenow hope to finish major work on the bill by June 14, but Stabenow told reporters earlier this week she thought the process might take two to three weeks and leadership aides have estimated a week and a half of floor time, pass or fail.

Senate Majority Leader Harry Reid (D-Nev.) said earlier this week he is willing to have an open amendment process on the bill as long as amendments fall within the purview of the legislation. The big question now is whether Republicans will demand amendment votes on proposals such as McCain’s, which are not directly relevant to farm or nutrition issues.

Roberts said Republican Senators had a “robust discussion” of the McCain sequester measure. If the GOP decides to push forward with that offering, or others on even more politically charged topics, it will throw off not only the desired timeline for wrapping work on the bill but also the chances the bill will be completed at all.

“It’s important to get this done,” Stabenow said. “At some point, if people are just trying to stop us, we have to go through all the procedural motions. But we want to work with everybody and do our level best to make sure that we can address people’s concerns.”

Correction: June 6, 2012

An earlier version of this story incorrectly stated the vote tally for passing the five-year authorization bill out of committee. The vote was 16-5.