Environmental groups are demanding more public documents from the State Department about a controversial oil pipeline that will cross the U.S.-Canada border, seeking information on half a dozen lobbyists and their firms connected to the Obama administration.

The new Freedom of Information Act request, which Friends of the Earth, the Center for International Environmental Law and Corporate Ethics International will file Thursday, is part of an ongoing campaign aimed at pressuring the administration to deny a construction and operating ­permit to TransCanada. The firm wants to construct a 1,700-mile pipeline to transport crude extracted from oil sands in Alberta, Canada, to Gulf Coast refineries. State has recently released a slew of e-mails in response to a FOIA that detail how a former campaign aide to Secretary of State Hillary Clinton, Paul Elliott, has appealed to the department’s officials to support the proposal.

Proponents say the pipeline will generate American jobs and supply oil from a U.S. ally; opponents say it will support an especially carbon-intensive form of oil extraction and could imperil American habitat and wildlife. The State Department has said it will make a final decision on the permit by the end of the year.

Two of the lobbyists named in the request — Gordon Giffin with McKenna Long & Aldridge and James Blanchard with DLA Piper — served as fundraising bundlers for Hillary Rodham Clinton’s 2008 presidential bid. Jeff Berman, a lobbyist listed on Bryan Cave’s Keystone XL lobbying account, directed delegate selection in President Obama’s primary campaign.

The groups are also asking for documents regarding McKenna Long & Aldridge lobbyist Maryscott “Scotty” Greenwood, who serves as a senior advisor and former executive director for the Canadian American Business Council, and the firm’s senior strategic adviser David Pollak. Greenwood is a Democrat who served on the Credentials Committee at the 2008 Democratic Convention. Pollak served as Co-Chairman of the New York State Democratic Party from 2006 to 2008, and was a Hillary Clinton Super-Delegate.

The FOIA request targets former Bryan Cave lobbyist Broderick Johnson, a former Clinton administration in the White House Office of Legislative Affairs from 1998-2000

The groups, which are represented by Earthjustice, based their request on documents compiled by another environmental organization, DeSmogBlog.

“The State Department has a legal obligation to make its communications with these lobbyists public,” said Earthjustice staff attorney Sarah Burt in a statement. “And we intend to do what we can to ensure the law is followed.”

The State Department and TransCanada could not be reached for comment late Wednesday.

— Juliet Eilperin