Senate Minority Leader Harry Reid will hold a special caucus on Wednesday morning to decide whether to kill the bill in order to block Sen. Tom Cotton's amendment. | AP Photo Dems block spending bill over Iran

Senate Democrats blocked the first spending bill of the season over Sen. Tom Cotton's attempt to force a vote on Iran, injecting controversy over the administration's nuclear deal into what had been a relatively smooth appropriations process.

The chamber voted 50-46 Wednesday against ending debate on a spending bill funding water and energy programs. But if the bill had advanced over the 60-vote threshold, Democrats could have been forced to vote on Cotton's Iran amendment, which Democrats believe amounts to a vote on a political "poison pill" intended to make them look bad.


"Our Democratic colleagues were great at dysfunction when they were in the majority and they're pretty good at it when they're in the minority," a stern Majority Leader Mitch McConnell (R-Ky.) said after the vote. "No matter the issue — no matter what the issue — there's some new and creative way to try and throw a monkey wrench into the gears."

Sen. Dianne Feinstein (D-Calif.), who was overseeing the funding bill on behalf of Democrats, said White House chief of staff Denis McDonough stressed to her that President Barack Obama would veto the legislation if the Iran amendment was included.

"Why can't we have the ability to do one bill in this house that doesn't have a poison pill on it, to set an example for future bills? ... Why can't a member see this?" Feinstein said. She took a dig at the freshman Cotton, adding: "Maybe he's a new member. Maybe he doesn't understand what the years have been."

Even more consequential, Democrats were frustrated at what they see as a breach of good-faith from Republicans on keeping controversial riders out of the appropriations process.

"We have been cooperative with them, we have avoided a lot of procedural votes, avoided all the filibusters of the past," Senate Minority Whip Dick Durbin of Illinois said. "But there reaches a point where they have to decide whether they want to move this process forward in a constructive way."

Calling Cotton's amendment "veto bait" for the White House, Durbin warned: "We can look over the horizon a little bit. We can see what’s coming."

Senate Minority Leader Harry Reid held a special caucus on Wednesday morning to decide whether to kill the bill in order to block the Cotton amendment, which would "prohibit the use of funds to purchase heavy water produced in Iran" — a vote sure to be portrayed as a referendum on Iran. It's a similar maneuver that Cotton pulled last year on a bill that allowed congressional review of the Iran nuclear deal, forcing his amendment into the queue and disrupting a bipartisan deal to vote on amendments.

The White House publicly stressed that Obama would veto the bill with the Iran language included.

"Senator Cotton has long made it clear that he will do anything to prevent the effective implementation of the Joint Comprehensive Plan of Action with Iran," White House press secretary Josh Earnest said in a statement Wednesday. "This amendment again demonstrates that Republicans have no intention of moving forward with a good faith effort to fund the government through the normal appropriations process."

In brief floor remarks Wednesday morning, Cotton defended his proposal as a necessary congressional response after the Obama administration announced last week that they were purchasing so-called "heavy water" from Iran. Heavy water is water that contains a higher-than-normal amount of deuterium and can be used in nuclear reactors.

His proposal is germane, which means it would've been allowed on just a simple majority vote if the bill had cleared the cloture hurdle. And Cotton said he had offered to hold it at a 60-vote threshold, or voice vote it so Democrats wouldn't have to go on the record.

"I, too, do not want to see the appropriations process end," Cotton said. But Cotton said he wanted to "ensure that the United States taxpayer is not subsidizing a critical component of Iran's nuclear industry, which I would add we are not required to do under the nuclear agreement with Iran."

His amendment would block taxpayer money for being used to buy heavy water from Iran. Republicans say the administration is essentially subsidizing Iran’s nuclear program and want to prevent any future deals over Iranian nuclear material.

Sen. Lamar Alexander (R-Tenn.), the chairman of the subcommittee overseeing the energy and water funding bill, said he was trying to work with Cotton to try to prevent his amendment from blowing up the appropriations process.

Nevertheless, "I think Sen. Cotton has acted responsibly," Alexander said. "He has acted as soon as he knew about the Department of Energy policy."

Still, Democrats said after the meeting that they viewed this move as just the initial shot in the GOP's efforts to weaken the nuclear deal via the appropriations process.

"There's a lot of resistance," said Sen Chris Murphy of Connecticut. "I think we misunderstand the Republicans if we think this is their first and last attempt."

A top Republican said they weren't ready to throw the towel in yet. "We're working on" resolving the issue, according to Senate Majority Whip John Cornyn (R-Texas).

Reid and McConnell had been making significant progress on the appropriations process, a major goal of McConnell's, until the Iran issue came up.

Nahal Toosi contributed to this report.