(CNN) - Deficit hawks in the Senate are working with leadership on an escape hatch just in case the Republicans' tax bill fails to generate the economic growth the party is anticipating.
The agreement was part of a deal to attract support for the tax legislation of senators like Bob Corker of Tennessee and Jim Lankford of Oklahoma, but now the party is grappling with how, exactly, they will implement it.
"At the end of the day, in a legislative body, you do the best you can with whatever opportunity you have to affect things in a positive way," Corker said. "I'm glad we were successful (Tuesday) in getting this agreement. Hopefully it's going to be memorialized and part of the bill. I haven't voted for a piece of legislation yet that I thought was just outstanding. Well, maybe. But not many."
Senators and aides are emphatic that the details of the trigger -- intended to increase taxes if the bill fails to generate enough economic growth -- are still very much in flux. There's division over whether automatic tax hikes should target the individual rates or the business side of the equation. After their Wednesday lunch, lawmakers also suggested that instead of the trigger setting off tax increases, it could instead require the party to cut discretionary spending.
While most lawmakers aren't drawing any red lines at this point, there is widespread concern in the conference that the trigger could backfire if the country enters a recession. They also worry that the trigger could interject uncertainty into the tax bill, something that lawmakers say could undermine the underlying goal of generating growth.
"I am not going to draw lines in the dirt and I'm not going to let the perfect be the enemy of the good," said Sen. John Kennedy, a Louisiana Republican who had said a day previously that he would rather "drink weed killer" than vote for a bill that automatically increased taxes.
Sen. Dean Heller, a Republican from Nevada, said, "Personally I don't support triggers."
"I think it takes away the kind of certainty that you have to put in this bill," Heller said.
Sen. Thom Tillis, a Republican from North Carolina, said he favored a proposal offered by Republican Sen. Ted Cruz of Texas that would force additional tax cuts if the growth outpaced the party projections but that he didn't like the idea of automatically raising taxes.
The struggle for leadership now is a classic one: How can they find a way to appease the deficit hawks without risking the votes of Republicans who aren't keen on the provision the deficit hawks are making a key condition of their vote?
Majority Leader Mitch McConnell can afford to lose only two Republican senators. There are three Republican senators -- Corker, Lankford and Arizona Republican Jeff Flake -- who have asked for assurances that the tax bill won't add to the federal budget deficit.
The trigger issue is only one of a few items that lawmakers are still working their way through just days ahead of an expected vote on the bill. Republicans are also looking at ways to give more tax breaks to pass-throughs, businesses that range from small stores to hedge funds and pass on their profits directly to the owner, who then pays taxes on the individual side.
Sen. John Hoeven, a Republican from North Dakota, said the party is working through a whole host of details but that in the end, the Senate passing the bill isn't the end of the road.
"Remember, this debate -- even once we pass a bill -- it still goes to conference," Hoeven said, where it must be reconciled with the House version of the legislation.