(CNN) - Republicans are bracing for the moment House Democrats formally request President Donald Trump's tax returns, attempting to fully understand the scope of a 1920s law that Democrats say gives them the power to obtain Trump's tax returns with a simple request.
Only one Democrat on Capitol Hill -- chairman of the House Ways and Means Committee Richard Neal -- has the power to request the return under the law. And even if he gets them, he doesn't unilaterally have the power to make them public without a vote of his committee. But, Neal has said he plans to ask for them. When exactly he will make that move is still under discussion.
Still, Republicans are beginning to set the groundwork for how they would have to respond if Democrats request a window into the President's closely-held financial holdings.
Senate Finance Committee Chairman Chuck Grassley, who also holds the power to request Trump's tax returns, has requested a briefing from the Joint Committee on Taxation about how section 6103, a provision in the IRS code that says a tax-writing chairman can request the tax returns of an individual -- would work.
Grassley's interest isn't in learning how to request the returns himself, but understanding how the process will work, the legal justifications behind it and the limits of the law as Democrats make their case that they are well within their rights to request the President's returns.
"I don't know how the process works, and I want to know the process," Grassley said.
Neal also told CNN he has "been in touch" with the joint committee.
"I believe they are going to be getting me some information into how (6103) plays out and our interest here is still in developing a case for this and not doing this in a willy-nilly fashion and sticking to precedent that has been used in the past," Neal said.
Trump did not disclose his tax returns during the presidential campaign despite the widespread precedent of modern candidates to do so. Trump has repeatedly cited being under audit as to why he has not disclosed his tax returns, though being under audit does not prevent anyone from sharing their taxes.
Members of the Senate Finance Committee say no clear strategy has emerged about how to rebuff Democratic efforts to ask for the returns nor are they sure how much power Democrats actually have.
"I am not sure if they have the legal backing to do it, but they sure have the will to do it," Republican Sen. Pat Roberts of Kansas said.
It's expected that any request from Neal to the Treasury Department would result in an extended legal challenge. Trump's lawyer Rudy Giuliani has signaled that Trump would fight a request for his taxes in court.
"They have to have a reason for wanting them and I fail to see a reason," Giuliani told CNN's Dana Bash last month. "They can't just look at them. It has to be linked to some wrongdoing."
"We will fight it in court and I think we would win unless they had some specific allegation," he added.
Sen. John Thune, the majority whip and member of the Senate's tax-writing committee, told CNN that the committee has had no formal discussions about how to handle a Democratic request for Trump's taxes.
"I just think for most people that has been litigated. That was a big issue over the course of his campaign and people voted for him," Thune said. "I think if you start down that path, that's kind of a slippery slope. I suspect that's precedent that you would create that in the future would get used again for that purpose, and sometimes the shoe may be on the other foot."
The ranking member of House Ways and Means has expressed concern about Democratic plans to obtain Trump's tax returns.
"The Ways and Means Committee's authority to request and make public any American's tax return under section 6103 is a provision to help Congress oversee the proper administration of the tax code. It should never be weaponized for political witch hunts against enemies," Rob Damschen, a spokesman for Rep. Kevin Brady, told CNN.
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