82% of Iran’s export revenues come from oil and gas.
If Israel hit Iran’s oil and gas refineries in the Persian Gulf Iran would probably attempt to close the Persian Gulf with missiles and drones against tankers.
In 2022 the seven Persian Gulf oil produces produced 32% of the world’s oil. They are Bahrain, Iran, Iraq, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates https://www.eia.gov/energyexplained/oil-and-petroleum-products/where-our-oil-comes-from.php
If the Persian Gulf was blocked by Iranian responses world oil and gas prices would increase sharply to the detriment of Harris's campaign.
This would be bad for Harris going into the 5 November Election as US voters would resent paying much more for "gas" (what Americans call petrol) at the pump. Would inflation figures would also grow significantly.
The current ailing Biden-but youthful Harris VP Administration would be blamed for all this - as the US Government is supposed to keep Israel and Iran under control in line with US national interests.
This may be why Israel might be waiting until after the US election to attack Iran’s oil/gas refineries.