I'm assuming that your S-corp held the event and not you personally, yes?
IRC 162(a) says, in part, "There shall be allowed as a deduction all the ordinary and necessary expenses paid or incurred during the taxable year in carrying on any trade or business". If holding events like this are "ordinary and necessary" for your industry (you don't say what that is), then I think you have the start of a good argument that the food is deductible.
Now, IRC 274(k) limits this by saying:
"(1)In general: No deduction shall be allowed under this chapter for the expense of any food or beverages unless—
(A) such expense is not lavish or extravagant under the circumstances, and
(B) the taxpayer (or an employee of the taxpayer) is present at the furnishing of such food or beverages."
For the first prong of this test, are these meals closer to rubber chicken dinners, or are we talking Wagyu filet mignon and Chateauneuf-du-Pape? Since you're the S-corp's owner, and you're present at the meals, the second prong should be OK. As long as the meals aren't "lavish or extravagant under the circumstances", the S-corp will be able to deduct them.
As for the amount deductible, IRC 274(n)(1) says that the amount deductible is limited to 50% of the cost, and IRC 274(n)(2)(D) makes an exception for
"(i) for food or beverages provided by a restaurant, and
(ii) paid or incurred before January 1, 2023."
If these meals were provided in 2023 or after, I'd say your deductible amount is limited to 50% of the cost.
Are you inviting politicians in order to lobby them? Then IRC 162(e) would seem to apply and deny any deduction.
More importantly, when you say you're "not on the payroll", you own an S-corp. If you're doing any work on the S-corp's behalf, the S-corp still needs to pay you a reasonable wage/salary that reflects your contribution, something reasonably comparable to what the S-corp would pay an employee to do those same things. Not doing so will be a big red flag for an audit--it's a common abuse of S-corps to not pay an owner who does work for the S-corp anything. You really don't want to roll those dice.
So, 1.) deduct half the cost of the food; 2.) pay yourself for your work; and 3.) attach a Form 8275 or Form 8275-R to your S-corp's return with your argument if you disagree with deducting only half the food or with paying yourself a reasonable salary for your efforts. (The standard you need to meet is a reasonable basis standard, IIRC.)