Despite vigorous GOP protests against Senate Majority Leader Harry Reid’s (D-Nev.) decision to use procedural tactics to limit amendments to the massive $288 billion farm bill, it remains unclear whether Minority Leader Mitch McConnell (R-Ky.) will be able to muster enough support to block the bill.

Reid made good Tuesday on his threat to “fill the tree” on the farm bill, a procedural tactic that allows him to essentially control what amendments can come to the floor.

Although Reid insisted that he would only use that authority to block non-germane amendments — such as proposals to permanently repeal the estate tax or Iraq-related provisions — Republicans accused the Democratic leader of hijacking the legislative process and vowed to block the bill.

“We are going to insist on a fair process. And, you know, we can sort of get this bill done the easy way or the hard way,” McConnell said Tuesday. “I think a better way to do it would be to understand that a bill of this magnitude is enormously significant, something we only do every five years. And the Republican minority is going to insist on an open process, which is what we will get to one way or the other in going forward. I don’t think that’s unreasonable.”

The Bush administration on Tuesday also released a Statement of Administration Policy criticizing the bill on a number of trade, tax and farm program reform fronts and vowed a presidential veto if changes are not made.

But despite the harsh words from Republican leaders, GOP sources acknowledged that it may be difficult for McConnell to muster enough support to block the bill until Reid opens up the amendment process.

Because of the size and scope of the farm bill — and the fact that supporters include numerous provisions aimed at luring support from as many lawmakers as possible across partisan and geographical lines — the measure is traditionally a difficult one for fiscal hawks to block, or leaders who oppose it to whip against.

“It’s every man for himself,” one GOP leadership aide said, adding that at this point it is unlikely that enough Republicans will abandon the bill to stall it.

However, the source did note that the current sour mood in Congress could aid opponents, particularly if consideration of the bill drags out over several weeks. “Everyone is so upset about everything around here, it may be a little bit easier of a lift than you might think,” the source said.