A Tuesday vote in the U.S. Senate offers some hope that populist pressure on Congress might challenge Wall Street's political power and influence over Washington.

The Senate voted 96-0 to approve an amendment to a financial overhaul bill mandating an audit of the Federal Reserve by the Government Accountability Office (GAO).

The idea of a Fed audit has been pushed by a few members of Congress, notably Rep. Ron Paul, R-Texas, and Sen. Bernie Sanders, I-Vt. Until this week, it was largely seen as a fringe idea, due primarily to pressure from Wall Street (the recipient of more than $2 trillion from the Fed) as well as opposition from the White House and the Treasury Department.

But anger over the Wall Street bailout and support for greater transparency in Washington, as well as frustration over the revolving door between Wall Street and Washington, is apparently being felt in Congress.

For most of its existence, the Federal Reserve has been a sleepy organization, known mostly for setting benchmark interest rates. But following the financial crisis of 2008-09, the Fed became involved in various federal bailout efforts, largely conducted behind closed doors.

An audit of the Fed was supported by Robert Reich, former Labor Secretary under President Bill Clinton, in a piece he wrote about what was missing from financial reforms taking shape in Congress. Reich argued in favor of a Fed audit, saying, "There's no reason the public should be kept in the dark about who benefits when the Fed departs from its traditional interest-setting role and chooses to provide credit (or in Fed parlance, 'open its discount window') to particular companies or entities."

Unanimous Senate support for a Fed audit is all the more remarkable given the recently reported fact that the top six banks have hired 240 former federal government officials, including 202 who used to work in Congress but who now work as lobbyists, to shape — meaning weaken — any financial overhaul measure that emerges from Congress.

In addition to a Fed audit, Reich supports a requirement that big banks spin off their derivative businesses, those hugely profitable, but highly risky, operations that were at the heart of the financial crisis.

The third requirement supported by Reich, but missing from the Senate's reform plan, is to cap the size of the largest banks — meaning break up the biggest financial institutions to address the "too big to fail" issue. If banks are limited in size, Reich suggests, it is less likely that the failure of one would trigger a domino effect that could threaten the national, or global, economy.

An audit of the Federal Reserve should make clear which of the nation's biggest banks were rescued with bailout money and which were not — and the reasons behind both actions.

An audit of the Federal Reserve also should reveal the financial benefit to the banks that have access to the Federal Reserve's "discount window," where they can borrow at artificially low interest rates and then turn around and lend that money, at substantially higher interest rates, to the U.S. Treasury by buying bonds. The big banks make a quick profit on this interest rate differential, while their lending to businesses — what banks are supposed to do — languishes at near record-low levels.

This ongoing, but below-the-radar, government bailout should be fully revealed and understood.

A Fed audit will bring some needed transparency to the actions of what has long been a secretive organization. It's beginning to be understood that, while the TARP (Troubled Asset Relief Program) spending got most of the coverage, it was actually other, less-visible programs through the Federal Reserve that provided the bulk of the government's $3.8 trillion in total bailout spending.

As Reich suggests, there is much more to be done if proposed financial reforms are to accomplish the goals of reducing the likelihood of another financial crisis and ending the too-big-to-fail mind-set that caused taxpayers to be forced into bailing out some of the nation's biggest financial institutions because of risky bets they had placed while making billions of dollars in profits.

The downside of Tuesday's Senate vote is that the amendment mandates a one-time audit only, a rollback from the original proposal for annual audits. But Sanders says he expects the one-time Fed audit to reveal so many backroom deals that the public will demand regular audits.

Pulling back the veil of secrecy from the Federal Reserve is a significant first step toward financial reform and transparency. But much more needs to done, and public pressure on Congress is the only way to resist Wall Street getting its way.