The development will be a huge embarrassment to May, who has already seen two chairs to the inquiry stand down since it was launched in July, both over conflicts of interest.
Here is a snapshot of where three of the active congressional inquiries stand.
The exception, and the one inquiry that stands out above all others, is that by Lord Justice Scarman into the Brixton riots in 1981.
The first two choices for inquiry chairman stood down.
Without a legislative response, the Senate inquiry would stand apart from its two comparable investigations of the past, said Loch K. Johnson, an expert on the CIA relationship with Congress.
Dr Liz Davies, who was a social worker in Islington and acted as a whistleblower there, said victims from the London borough had adopted a policy of "absolute non co-operation" with the inquiry as it stands.
That's the danger in this book: a serious inquiry won't stand a chance of getting much attention now.
All the representatives for the victims want someone to head the inquiry who can stand up to the establishment.
In a statement, the European Commission said that the latest subsidy inquiry was "a stand-alone investigation" with no direct link to the panel inquiry and could take up to 13 months.
He thanked President Bush and Secretary Powell for helping avoid the inquiry, saying, "They stood firm in order not to allow that Israeli soldiers will be interrogated".
