Interior Secretary Ken Salazar's announcement this morning that he will resign from the agency in March has sparked a fresh round of Beltway gossip about who may replace him.

While a White House spokesman this afternoon declined to speculate on who the president might pick -- and when -- many agency observers assume the nominee will hail from the West, where Interior manages the bulk of its lands.

Former Washington Gov. Christine Gregoire (D) has emerged as a leader among several potential candidates, even though her name has also been floated as a potential nominee for U.S. EPA administrator or secretary of the Transportation Department.

Gregoire, who earlier this week wrapped up an eight-year run as governor, is a former state attorney general -- as Salazar was -- and was also the head of Washington's Department of Ecology in a state that is 30 percent owned by the federal government. Her office has worked closely with Interior's National Park Service, Bureau of Land Management and Bureau of Reclamation, among other agencies.

Some Capitol Hill insiders have said Gregoire favors the Interior position over EPA. A former Gregoire spokeswoman did not reply to an email for comment this afternoon.

There's no shortage of other former elected officials on the list of possible appointees, including Rep. Norm Dicks (D-Wash.), who retired this month after 36 years in Congress, much of it spent as an appropriator overseeing the Interior budget.

Dicks was an outspoken advocate of the Endangered Species Act, opposed lifting a moratorium on offshore oil and gas leasing in the Atlantic and Pacific oceans, and was a forceful voice for confronting climate change.

As such, a Dicks nomination may face resistance in the hyperpartisan Senate, where past Interior nominees have been blocked for being perceived as too pro-environment.

Former Sens. Byron Dorgan (D-N.D.) and Bob Kerrey (D-Neb.) have also been touted as potential nominees. While both may have a clearer road to confirmation, Dorgan, who is known for brokering bipartisan agreements on energy, is seen as a more likely pick to replace Energy Secretary Steven Chu if he decides to retire.

Four other former Democratic governors have also been mentioned as potential candidates: Bill Ritter of Colorado, Brian Schweitzer of Montana, Dave Freudenthal of Wyoming and Bill Richardson of New Mexico.

While all of those candidates hail from states flush with public lands, Freudenthal and Schweitzer in particular would be viewed favorably by the oil and gas and coal industries.

Schweitzer, who some speculate is eying a future run for president or for Sen. Max Baucus' (D-Mont.) seat, supports the Keystone XL pipeline and backed a controversial plan to lease state-owned coal but has also pushed development of his state's massive wind resources.

Some insiders have also speculated the president may seek Sen. Mark Udall (D-Colo.) for the job.

Udall, whose uncle Stewart Udall served as Interior secretary in the 1960s, is an outspoken supporter of wind energy and is chairman of the Energy and Natural Resources Subcommittee on National Parks.

His selection would put a Democratic seat in play in 2014 and could threaten the party's slim majority in the Senate. Udall spokesman Mike Saccone said the senator has no ambitions to become secretary.

"Sen. Udall is looking forward to continuing to serve the people of the great state of Colorado in the U.S. Senate now and after his successful re-election campaign in 2014," Saccone said.

With this morning's announcement, a coalition of liberal environmental groups renewed their push for the president to nominate Rep. Raúl Grijalva (D-Ariz.), the top Democrat on the House Natural Resources Subcommittee on Public Lands and Environmental Regulation.

Grijalva, who was in the running for Interior secretary in 2008 but was seen by some in the White House as too critical of offshore oil and gas drilling, has been a firm backer of Salazar's decision to withdraw a million acres surrounding the Grand Canyon from future mining claims and has called for greater use of the Antiquities Act, which many Western Republicans oppose.

"Will the president try to make the Interior Department an agency for all the people, or merely a lobbying stop for select industrial interests like oil and gas?" asked Bill Snape, a senior attorney at the Center for Biological Diversity, which has lobbied for a Grijalva nomination. "That question will be answered by who he picks to lead this department, with jurisdiction over public lands, wildlife, water resources and natural values."

As he did months ago, Grijalva today said he was flattered by the groups' proposal but is happy representing his southern Arizona district.

A Grijalva nomination would be a gift to the president's environmental base but is unlikely to survive a Senate confirmation battle.

While there has been a long tradition of nominating Westerners, it is entirely possible the president will nominate Interior Deputy Secretary David Hayes, a native of Rochester, N.Y., who first served in his post during the Clinton administration.

Hayes has led much of the behind-the-scenes work supporting Salazar's policies, including an interagency working group to expedite permitting of energy projects in the Arctic.

One dark-horse candidate is John Berry, a former Interior assistant secretary for policy, management and budget who now serves at the Office of Personnel Management.

If picked, Berry would be the only openly gay member of the president's Cabinet.

Some conservationists said they would support the nomination of Sally Jewell, the CEO of Recreational Equipment Inc. (better known as REI), a pick that would recognize the role of public lands in buttressing the recreation industry.