Some Senate Democrats and even some Republicans are concerned about a controversial trade deal known as the Trans-Pacific Partnership, which critics have denounced as “NAFTA for Asia.” And they are making their opinions known to the Obama Administration about the relative secrecy under which the deal is being negotiated.

As first reported by Zach Carter of the Huffington Post, Sen. Ron Wyden, the chair of a key Senate subcommittee on international trade, was denied access by the Office of US Trade Representative to any of the draft documents of the TPP. Eventually, after introducing legislation to try and force openness on the process, Wyden did gain access, but his staff did not, including those with key insight on trade policy.

That’s better than nothing, Wyden spokeswoman Jennifer Hoelzer told HuffPost, but not helpful from a practical standpoint, given that congressional staff perform much of the legislative work on Capitol Hill.

“I would point out how insulting it is for them to argue that members of Congress are to personally go over to USTR to view the trade documents,” Hoelzer said. “An advisor at Halliburton or the MPAA is given a password that allows him or her to go on the USTR website and view the TPP agreement anytime he or she wants.”

The general public and most nonprofit organizations have no access to the documents, although a number of corporate officials can see them.

Now a letter is being circulated on the Hill, though language has not been finalized, demanding that USTR chief Ron Kirk provide more transparency to the process and allow Congress to oversee their work on TPP. The letter will call on Kirk to immediately post summaries of all the proposals for TPP on the USTR website. This is only the latest action for additional transparency, the boldest of which was Darrell Issa leaking the entire intellectual property chapter on his website.

I spoke with Sen. Sherrod Brown (D-OH), a longtime opponent of NAFTA-style trade deals who is organizing the effort to open up TPP, at the Netroots Nation conference in Providence, RI. He expressed concern about two major areas of the trade pact being negotiated between the US and a series of Asian and Pacific nations. First, he highlighted the investor-state relations element of recent trade deals, where companies are given the capacity to override existing public health and safety standards inside other countries by virtue of the trade agreement.

And like Issa, Brown has concerns about the IP issues. “In the past this was mainly confined to pharmaceutical patents,” Brown said, and while that’s a continuing problem in the TPP (the result of which could drive up drug prices in poor countries across Asia), “in the age of the Internet, there are a host of other IP implications that need to be addressed.” The same coalition that opposed SOPA and PIPA has worried about the IP implications for TPP. Brown wants the USTR to allow pro-Internet freedom stakeholders access to the documents, not just industry, by putting them on the Industry Trade Advisory Committee (ITAC) for Intellectual Property Rights, the key IP advisory body for the deal.

There are additional potential impacts of TPP in areas like natural resources, land use, food, government procurement, energy, telecommunications and financial regulations. With the number of countries involved, this would be as big a trade deal as has been undertaken in decades.

Brown couldn’t really get specific about his complaints with TPP, because like most people he doesn’t know all of what’s in the document. So he’s going this route, working with others in Congress, to try and get some input into the deal. The letter basically warns that Congress and the public need to weigh in on the deal before they get frozen out of the process. Otherwise, it will be presented to Congress fully negotiated, in a “take it or leave it” fashion. This has been the history of recent NAFTA-style trade deals.

“(USTR) say they don’t want to negotiate in public,” Brown told me. But the asymmetry here was troubling to him. “It’s easier for a CEO to view the end product than a member of Congress, that’s the problem.”