Sen. Tom Cotton is insisting on simple majority votes on contentious amendments to legislation to provide congressional review of any final nuclear deal with Iran, apparently stymieing the possibility of moving forward, at least for now.

The Arkansas Republican sought to line up a pair of amendments that supportive Democratic senators have said could cause them to remove support for the bill. One of those, sponsored by Cotton, would require Iran to allow inspectors full access to suspicious sites. The other, led by Florida Republican Marco Rubio, would require Tehran to recognize Israel’s right to exist.

“I think some of the tactics that are now being deployed are going to make it much more difficult for us to be able to proceed in an orderly way,” Foreign Relations ranking member Benjamin L. Cardin said.