While any candidate who jumps into for the US Senate will be sure to start raising money, some potential candidates already have a head start. They already have federal campaign committees formed, and even if the committees are for some other office, the cash can be transferred to a Senate run.
The most recent "cash on hand" reported for the federal campaign committees of selected possible candidates -
JD Hayworth - $148,224.47
Jeff Flake - $627,851.61
John Shadegg - $154.99
David Schweikert - $16,308.33
Ruth McClung - $107,649.87 (included because she has so much cash on hand)
Jonathan Paton - $12,389.26
Ben Quayle - $7607.04
Ed Pastor - $1,391,936.29
Gabrielle Giffords - $285,501.24
Raul Grijalva - $30,621.77
Ann Kirkpatrick - $13,896.86
Just for giggles -
Joe Arpaio - $2,829,160.00
That number is worthy of giggles because while it dwarfs every other potential candidate's cash on hand, it doesn't matter - it's for his county sheriff candidacy and cannot be transferred to a federal committee.
While there has been a little internet chatter over a possible Pastor candidacy and his well-stocked campaign warchest and some of the other potential candidates have little or no cash for a federal campaign, once a legit candidate enters the race he or she will be able to raise money quickly.
Of course, they'll have to. :)