WASHINGTON ( TheStreet) -- The list of TARP deadbeats has been growing in size and scope, and proposed changes in capital requirements could put even more institutions at risk of falling behind on their bailout tabs with Uncle Sam.

The U.S. has tallied $2.6 billion worth of failed TARP investments to date, and lost part of its investments in four other banks in exchange for private recapitalization. Initially worth $911 million, the Treasury Department accepted haircuts ranging from roughly 17 cents on the dollar to 38 cents on the dollar, to woo private equity investments for Sterling Financial ( STSA), Pacific Capital ( PCBC) and Hampton Roads ( HMPR) , and secure a buyout deal for South Financial Group ( TSFG).

The government lost $216 million on the South Financial deal , though it's hard to tell the ultimate outcome for the other transactions, since the government will continue to hold a stake over time.

Perhaps more troubling is a growing list of delinquent banks. That list now stands at 81 firms that represent $2.2 billion in taxpayer dollars. Those numbers seems sure to grow when new capital rules are implemented, since the financial reform bill may not allow banks to use trust preferred securities in Tier 1 calculations. The proposed rule change will leave many small banks struggling to plug capital holes all at the same time. It could also force the Treasury to convert more of its preferred stock into common equity, or take additional haircuts to incentivize private players to cough up more cash.

Still, the size of the Treasury's at-risk investments stood at an average of just $28 million per delinquent bank, as of April 30. The largest, a $300 million investment in Citizens Republic Bancorp ( CRBC) remains a concern, but with capital levels well above the "10-6-5" ratios that the Federal Reserve requires of a well-capitalized bank, Citizens Republic may not yet be entirely in the danger zone.

The other worrisome investment was $1.55 million put into Saigon National Bank ( SAGN). The West Coast bank has missed six dividend payments, thereby giving the Treasury the right to elect two board members, as it did with American International Group ( AIG) earlier this year .

There are 660 or so banks that have yet to repay TARP, but have stayed current on quarterly dividends at the same time. While many of them seem to have a good grip on their troubled loan portfolios, the financial reform bill's proposed capital standards pose a different kind of threat. Rochdale Securities analyst Richard Bove recently identified 58 banks that are "most in jeopardy" - in other words, most need to raise capital - if the strict standards pass.

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