The pathway to approving a bipartisan energy modernization bill in the Senate flows through the corroded, toxic water pipes of Flint, Mich.

Hopes were high last week to quickly advance the bipartisan energy measure, championed by Senate Energy and Natural Resources Committee Chairwoman Lisa Murkowski, R-Alaska, and Sen. Maria Cantwell, D-Wash., top Democrat on the panel. Their committee approved the measure 18-4 last summer. Lawmakers haven’t successfully advanced an energy package this broad in nine years. The plan bolsters liquefied natural gas exports, backs up the power grid and boosts alternative fuels like geothermal and wind.

But everyone on Capitol Hill knows what is the bete noire of legislation: so-called “poison pill” amendments that can kill any bill they touch. And a bid to aid the beleaguered community of Flint is playing that role this time.

Naturally, if a said “pill” is “poison,” the level of virulence is in the eyes of the beholder.

Last week, Senate Democrats proposed latching a $600 million amendment to the energy bill to aid Flint, which is suffering from contaminated water. The money would go toward overhauling Flint’s waterworks and to study other issues with lead pipes.

The Democrats’ plan may not have been a “poison” pill in the truest sense of the term. But the amendment in question was certainly about poison. And Republicans recoiled at the Flint amendment. Their objection certainly wasn’t a suggestion to abandon Flint. Rather, GOPers wondered about spending money without requisite offsets.

Was it a “blank check?” Did it set a bad precedent for the federal government to bail out other localities from near-certain additional infrastructure woes? Did this constitute an “earmark,” a congressional set-aside of money (now banned) for a specific project in a specific state or congressional district?

There was an operational problem. There could be what’s referred to in congressional parlance as a “blue slip” issue. Article I, Section 7 of the Constitution requires spending measures originate in the House. It’s possible that the “spending” that could be tacked onto this energy plan via the Flint amendment could violate that constitutional edict and prompt a “blue slip.” A blue slip parliamentary phenomenon on the energy plan could halt the bill in its tracks in either body. A senator may be able to challenge whether the Senate broke its rules by making a “point of order.” Or, if the Senate ever did approve the bill, the House could cite the constitutional “origination” argument and detonate the measure.

Late Wednesday night, Murkowski came to the Senate floor to note that legislative traffic had been light all day. In fact there was a possible trajectory on Tuesday to wrap up the energy bill Thursday. But that pathway seemingly dissolved Wednesday evening. The Alaska Republican said that much of the negotiation and bargaining unfolded “off-stage” – which is customary in the Senate. But when Murkowski spoke, she didn’t have a battle plan to offer or an agreement on amendments to immediately usher the energy bill to passage. There was no deal on the Flint amendment.

And so the Senate stares at a procedural vote later Thursday that could very well ice the energy legislation. A failure to marshal 60 yeas stymies the bill – mostly over no resolution on Flint since Democrats aren’t willing to vote to shut off debate. Democrats were clear that they may halt the energy bill unless there is a vote to help Flint.

Perhaps the most-telling signal that the energy bill faced trouble came when Senate Majority Leader Mitch McConnell, R-Ky., came to the floor earlier to tee up a debate and vote on another piece of legislation: sanctions against North Korea.

McConnell designed a roadmap to launch debate on the North Korea bill next Wednesday with a final vote coming shortly thereafter. Pyongyang says it tested a hydrogen bomb in January. The House immediately voted almost unanimously to discipline North Korea.

It’s not unheard of for the Senate to prep an additional bill for debate while toiling with another one. But in this case, the Senate’s semiotics indicate the body could be ready to skip to something else unless senators can resolve the Flint water amendment soon. Still, if supporters of the bill can muster 60 yeas, the measure is on a glide path to passage. That means those backing the Flint amendment are out of luck anyway. And if not, Democrats will have made their point and will race to the microphones to declare Republicans as calloused toward the people of Flint.

Flint and its septic water exploded into international headlines over the past two months. As senators wrestled behind the scenes Wednesday with amendments to the energy bill, members of the House Oversight Committee tangled on-stage with witnesses called to discuss the crisis. There are sure to be other hearings probing what went wrong. And Congress is about to start the annual appropriations process. Sympathetic lawmakers will try to tie funds tagged for Flint to those measures, too.

Flint could very well sideline the Senate energy bill. If it does, that’s the marker indicating that legislative attempts to assist the beleaguered city are only beginning in Washington.

Capitol Attitude is a weekly column written by members of the Fox News Capitol Hill team. Their articles take you inside the halls of Congress, and cover the spectrum of policy issues being introduced, debated and voted on there.