The battle to control the GOP convention in Cleveland — and the fate of party — has reached a turning point.

While the “Stop Trump” movement has unleashed a barrage of cross-country phone calls and emails to seek support for their proposals, a group of longtime Republican rule makers, some working with the Trump campaign, have quickly coalesced to try and block them.

Those Republican rule makers are also going on offense by proposing what would be relatively historic changes in order to take some power away from convention delegates this year and close more primaries to non-Republicans the next time around.

There are no rules for the Republican Convention. Not yet.

The rules will be determined the Thursday and Friday before the convention by the 112-member (aptly named) Convention Rules Committee. Traditionally those rules control the convention and govern the next four years for the party.