The U.S. Senate’s simmering debate over climate science has come to a full boil today, with lawmakers trading feisty remarks as they prepare to vote on at least two measures offered by Democrats that affirm that climate change is real—with one also noting that global warming is not “a hoax.” A Republican Senator, meanwhile, is offering another climate amendment that doesn't address whether global warming is real, but encourages the development of clean energy.

In an effort to highlight their differences with some Republicans on climate policy, several Democrats have filed largely symbolic amendments to a bill that would approve the Keystone XL pipeline. They are designed to put senators on the record on whether climate change is real and human-caused. The backers are now pushing for votes on those measures as soon as today.

The Democratic amendments vary in detail and whether they call for specific actions on climate policy. But they share one thing in common: that lawmakers should at least accept climate science, regardless of party affiliation. “We may not agree on the solutions, on the paths forward, or even on some of the details, but I do believe it’s time for us to begin to agree on a basic set of facts,” said Senator Brian Schatz (D–HI), who is offering a climate amendment, on the Senate floor today.

Republicans immediately called the Democrats’ efforts a distraction. “If you’re using climate change as a reason not to build this pipeline, you’re kidding yourself or you’re misleading the public,” said Senator Lindsey Graham (R–SC) during the debate. “It has absolutely nothing to do with the issue in this regard.”

The Senate is likely to take up at least two Democratic amendments. The first, Schatz’s amendment, cites scientific bodies like the National Research Council and Intergovernmental Panel on Climate Change in asking whether it’s the “sense of Congress” that “climate change is real” and that “human activity significantly contributes to climate change.”

The second amendment, from Senator Sheldon Whitehouse (D–RI), asks simply whether it is “the sense of the Senate that climate change is real and not a hoax." It takes a veiled jab at Senator James Inhofe (R–OK), who has called climate change a hoax.

It’s unclear whether any of the amendments can get even a simple majority in the GOP-controlled Senate. But, potentially throwing in a higher bar, Senator Lisa Murkowski (R–AK), chair of the Senate Energy and Natural Resources Committee, suggested that “non-germane” amendments would need 60 votes instead of 51 to win adoption.

She didn’t explicitly say that the climate amendments are nongermane. But she strongly hinted that she saw the two climate amendments as a sideshow to the Keystone XL debate.

“I do find it a little bit ironic … neither one of them actually quotes the parts of the State Department final [environmental assessment] that explains, I think in pretty fair detail, that this project will not significantly contribute to climate change,” Murkowski said on the Senate floor.

Amy Harder of The Wall Street Journal reports that "Republicans are responding with an amendment from Sen. John Hoeven of North Dakota" that quotes from a section of the State Department which states that "the proposed pipeline would produce fewer greenhouse gas emissions than an alternative mode of transportation, such as rail. The Hoeven amendment says it’s the sense of Congress that it should reject any federal policies that increase the cost of energy and hurt jobs. It says Congress should put a priority on policies that enable innovation and that could lead to clean sources of energy, but it does not specify what policies those are and does not address whether climate change is real. Mr. Hoeven’s amendment is designed as an alternative for moderate Republicans who may be worried about going against a scientific consensus on climate change."

Senator Bernie Sanders (I–VT), a Democratic-aligned independent, has suggested that he would push for a vote on an another amendment of his own, but it wasn't on the Senate's agenda for the day. His amendment states not only that scientists agree that climate change is real and human-caused, but that society needs to shift from fossil fuels toward cleaner energy.

*Update, 21 January, 3:26 p.m.: This item has been updated to include information on the Republican amendment.