That would be the Pro Cycling Tour.
ASO (predictably taking the lead) is excluding Unibet from Paris-Nice, making good on its threat to limit Pro Tour teams to 18 invitations at races run by the Grand Tours. The idea is that, before the UCI started refilling empty slots, the list was down to 18 teams... a number that represented an acceptable compromise to the Grand Tours on a key issue of debate between the Greeks and Carthaginians of modern Cycling. Eighteen this year, and wind it down to 15 in a couple years, and we've got the makings of a deal.
But the Pro Tour is sticking to its guns and re-upped with Unibet and Astana to get back to 20 teams, its preferred number. Paris-Nice is the first Pro Tour race, and happens to be an ASO product as well, so this stalemate was due to kick into overdrive. And so it has.
FWIW, I don't particularly care how it comes out, as long as it does. I've stated before that 15 is a large enough sample of teams to make the Pro Tour great, but I have no problem with the last five teams either. Next step? I'm guessing a judge will be involved.