Senate Majority Leader Mitch McConnell blasted Democrats Thursday morning for blocking an energy and water funding bill over an amendment on Iran.

McConnell took to the Senate floor to chastise Democrats for backing away from the Energy and Water Development and Related Agencies Appropriations Act Wednesday, when a vote to close debate on the bill failed to reach 60 votes. Democrats are upset over Arkansas Sen. Tom Cotton’s amendment to the bill that would ban the Obama administration from buying heavy water, which is used to make nuclear material, from Iran in the future.