Unless as noted the TSO is holding your BP (which you don't need if you are not flying today, though it does have your name and ticket number so they can look up your PNR info) or worse your ID which you would walk away without. You need your DL to drive home.

From an alleged 2009 copy of the TSA Screening SOP available on the interweb. No SSI redacted information in this section. Bolding Mine

"2.11. INDIVIDUALS WHO REFUSE SCREENING OF THEIR PERSON

The screening process of an individual begins when he or she walks through a WTMD (or an ETP if it is placed ahead of the WTMD at ETP-equipped checkpoints), or a TSO grants an individual’s request for specialized screening. Once screening has begun, an individual may not withdraw from the screening process.

A. If an individual refuses screening of his or her person before screening has begun, the TSO must deny the individual entry into the sterile area.

B. If an individual refuses to complete screening after screening has begun, the TSO must notify the STSO. The STSO must advise the individual that the screening process must be completed. The STSO must then offer the individual a final opportunity to complete the screening process. If the individual continues to refuse screening, the STSO must:
1) Notify an LEO and request that the LEO assist in completing screening of the individual
2) Ensure that screening of the individual’s accessible property is completed
3) Inform TSA management if the LEO permits the individual to return to the public area without completing screening

C. If the individual, who has refused to complete screening, returns to the public area prior to clearance or the arrival of an LEO:
1) Screening personnel must attempt to keep the individual under constant observation until an LEO arrives.
2) Screening personnel must not physically detain or hinder the movement of the individual.

D. If an unscreened individual proceeds into the sterile area, all screening at that screening checkpoint must be stopped and no other individuals are permitted to enter the sterile area until directed to resume screening operations by TSA management."

So we learn in Section B1 that the TSO requests the LEO to force the completion of the screening, but the LEO has the option to refuse and simply point the person back to the public area, as noted in B3.

Section C is very clear about walk offs and the TSO's power to detain: None. ^

Of course there is always the catch all "interfering with the screening process" to charge you with.