The manufacturers have suspended less popular bullets to try to meet demand for the more popular ones. .303 British just isn't that popular state side and the Canadian market is so tiny in comparison there is no profit incentive for the manufacturers to produce the ammo. They are corporations who need to make money to survive so they can't do a favour for Canadians if it will cost them money and put them behind their competitors. Either the crazy, heightened levels of demand will subside and manufacturers can catch up again, or manufacturers will expand to increase production if they think it's a long-term demand. Pretty much all the US manufacturers are running 24-hours to try to meet demand. Building new production facilities can take years and cost tens of millions in capital investment which is a huge risk if demand slumps.
I don't see how an election will change anything. The panic buying that caused the shortages was caused by media hype, not legislation. Obama has only passed one significant piece of firearms legislation and that was banning the import of the Korean M1 carbines and garands. That had little to no effect on ammunition and component shortages. No limitations have been put on the manufacturers and they themselves say over 90% of the extra demand causing the shortages is civilian retail demand, not military or law enforcement. I don't like Obama, but all the evidence points to us being the problem, regular consumers, not Obama, the democrats, or anyone else.
I've only been reloading for a few years so haven't been around long enough to see out the long game but many old timers say the industry goes through 3-5 year cycles. The current shortages started right after the Sandy Hook shooting in December 2012 when people started panicking and saying that Obama was going to ban guns or legislate limits on firearms and ammunition (which he never did and wouldn't have passed the Republican-majority congress if he tried). People emptied store shelves across the US so suddenly there was a huge spike in demand. Empty shelves caused many not in the initial panic to in turn panic as there now really was a shortage due to panic buying. That caused the warehouses and wholesalers to sell out their stockpiles and the manufacturers have been playing catch-up for almost two years. It's all one huge snowball effect. If these 3-5 year cycles hold true we should see some stability again in the next year or two. I'm not talking about prices dropping to pre-panic levels, I doubt that will happen, but just store shelves being well stocked again with a decent supply of ammunition and components. That includes .311" and .312" diameter bullets.