WASHINGTON -- House Democrats took the political offensive on Keystone Wednesday, seeking to probe connections between the multi-billion dollar project and Koch Industries, the Kansas-based energy conglomerate that has funded many a conservative cause.

At a hearing before a subcommittee of the House Energy and Commerce Committee on Wednesday, Rep. Henry Waxman (D-Calif.) called for subpoenaing representatives from Koch Industries over their alleged financial stakes in an approval of Keystone XL, arguing the committee has an "obligation" to understand who would benefit if the controversial oil pipeline was constructed.

The comments come just one week after Obama rejected a permit for the pipeline, which would stretch from tar sands in Canada to refineries in Texas, saying Republicans had jeopardized the review process by requiring the administration to render a decision by Feb. 21.

In a letter to subcommittee chairman Rep. Ed Whitfield (R-Ky.) asking for the subpeonas, Waxman and eight other House Democrats called for a day of hearings featuring Koch Industry executives. They cited, as evidence for their suspicion, a Koch subsidiary's assertion during a Canadian proceeding that the company has a "direct and substantial interest" in the pipeline.

"Last year news organizations reported that one company, Koch Industries, would be one of the big winners if this pipeline were constructed," Waxman said at the hearing. "We asked Koch whether this was true and were told they have no interest whatsoever in the pipeline. But then we learned that they told the Canadian government that they have a direct and substantial interest. Something does not add up."

A visibly ruffled Whitfield cut Waxman off, saying that while he would certainly accept the letter, he had no intention of subpoenaing the Koch brothers. "The brothers have nothing to do with this project," he said.

When Waxman pressed him on the issue, Whitfield pivoted to House Republican's favorite defensive talking point on the subject of clean energy.

"If you want to talk about that, let's talk about the millions of dollars the Obama administration gave companies like Solyndra and people like George Kaiser and other campaign bundlers," Whitfield said.

Solyndra, the California solar panel manufacturer and Department of Energy loan recipient that went belly-up last year, has nothing to do with the Keystone XL decision. And by that logic, Whitfield's comment would seem to acknowledge that he and Waxman were simply trading partisan barbs.

The bickering came during a hearing over a bill introduced by Rep. Lee Terry (R-Neb.) that would strip Obama's State Department of the power to approve the pipeline, passing it to the independent Federal Energy Regulatory Commission. The bill would also require the FERC to issue approval of the project within 30 days.

Kerri-Ann Jones, the State Department's point person on Keystone, on Wednesday dismissed the proposed legislation, arguing it "imposes narrow time constraints and creates automatic mandates that prevent an informed decision." The panel is slated to meet again on Feb. 1.

Watch Mediaite's video of Waxman and Whitfield's heated exchange below: