The latest public airing of congressional tensions over the Keystone XL pipeline is set for Friday, but its deepest partisan schism is coming over a witness uninvited by Republicans.

The House Energy and Commerce Committee's top Democrat, Rep. Henry Waxman of California, today continued to poke the GOP majority over its decision not to seek testimony on Keystone XL from energy conglomerate Koch Industries.

Democrats have long suggested that Koch, known for ties between its two founders and tea party groups that often aim to undercut President Obama's agenda, stands to financially benefit from the pipeline despite its denials of the charge.

Waxman lamented in a letter to Energy and Commerce Chairman Fred Upton (R-Mich.) and Ed Whitfield (R-Ky.), his top subpanel chief, that "Koch Industries is receiving special treatment" following a request that he and Rep. Bobby Rush (D-Ill.) filed last week asking for the company to testify at the committee's next Keystone XL hearing (E&ENews PM, Jan. 23).

"If our committee is going to consider legislation that earmarks a specific energy project for approval, members have a right to know who will benefit," Waxman wrote. "Your priority should be promoting transparency, not shielding Koch from legitimate questions."

Waxman also released a Monday letter from Whitfield to Koch that reiterates the Kentuckian's refusal to endorse the Democratic request for testimony from the company.

"Members on both sides of the aisle support this project because of the immense benefits it holds for the national interest, not because of any interest or lack thereof on the part of any individual organization," Whitfield wrote, dismissing the Democrats' bid as an attempt to slow down a GOP plan to fast-track Keystone XL. "We would no sooner compel an individual such as Warren Buffett to appear simply because he stands to benefit financially from denial of the pipeline."

A GOP committee source later clarified that Whitfield's letter served as an invitation, on behalf of the minority, for Koch to appear.

Republicans' invocation of Buffett, whose support for higher capital-gains tax rates has made him something of a Democratic icon, as a counterweight to the Koch name began last week, during the first installment of the Energy and Commerce Committee's hearing (E&ENews PM, Jan. 25).

The GOP logic behind bringing up Buffett tracks largely with Waxman's reasons for mentioning the Koch brothers. Democratic charges that their company would profit from the $7 billion XL link -- an assertion that Koch strongly denies -- stem from the firm's application for "intervenor status" during Canadian regulatory review of the pipeline connecting Alberta's oil sands with Gulf Coast refineries.

Multiple other stakeholders that would not reap direct financial profit from the XL project, including environmental groups that oppose greater consumption of its emissions-heavy fuel, also sought that "intervenor" designation. Similarly, the GOP suggestion that Buffett might profit from Obama's rejection of Keystone XL stems from the resulting shift of oil sands crude transportation to multiple rail lines, including the Burlington Northern railway that the Nebraskan magnate owns.

The Energy and Commerce Committee has yet to release a complete list of witnesses for Friday's hearing, which touches on legislation from Rep. Lee Terry (R-Neb.) that would remove the pipeline from Obama's jurisdiction and spur its approval by the Federal Energy Regulatory Commission. Republican leaders plan to attach the Terry bill to their long-term transportation measure, if it does not come to the floor as part of a payroll tax-cut package now being negotiated with the Senate.

But committee Democrats disclosed the group of invitees they sought -- in addition to Koch, it includes a Nebraska rancher who has mobilized local opposition to Keystone XL and a representative from pipeline sponsor TransCanada Corp. Other witnesses sought by Waxman's party include representatives from the Army Corps of Engineers and the Bureau of Land Management, which typically help work out permits and approvals for large-scale infrastructure such as pipelines.

A Democratic committee source said the BLM and Army Corps witnesses would "testify about how the Terry bill removes current permitting duties that protect clean water and achieve other goals."

Click here to read Whitfield's letter to Koch.

Click here to read Waxman's letter to Upton and Whitfield.

Schedule: The hearing is Friday, Feb. 3, at 10 a.m. in 2322 Rayburn.

Witnesses: TBA.