WASHINGTON — Interior Secretary Ryan Zinke says Senate Democrats are holding the department's nominees "hostage" to a political agenda that includes opposition to his review of presidentially designated monuments.

In a sharply worded letter to Illinois Sen. Dick Durbin, the Senate's No. 2 Democrat, Zinke said it's unfortunate that Democrats have placed holds on four Interior nominees, including the department's top lawyer and budget chief.

The nominees "have nothing to do with this monument review, yet they have been forced to sit on the sidelines" for months, Zinke wrote Thursday. "As a former Navy SEAL, this is not the type of hostage situation I am accustomed to."

Zinke offered to meet with Durbin, who requested a briefing last month along with other Democratic senators to discuss the monument review.

President Donald Trump ordered the review this spring following complaints by congressional Republicans that previous presidents had misused a century-old law intended to protect federal lands, creating oversized monuments that hinder energy development, logging and other uses. Trump called some monument designations by his Democratic predecessors "massive land grabs."

Zinke has recommended that Trump shrink four large monuments in the West, including the sprawling Bears Ears and Grand Staircase-Escalante national monuments in Utah.

Zinke also recommended that Nevada's Gold Butte and Oregon's Cascade-Siskiyou monuments be reduced in size, although exact details remain unclear. The proposals have prompted an outcry from environmental groups and Democrats who accuse Trump and Zinke of engaging in a secretive process aimed at helping industry groups that have donated to GOP campaigns.

Opponents have promised to take the Trump administration to court to block any attempts to rescind or reduce the monument designations. Former Presidents Barack Obama and Bill Clinton designated the monuments under the 1906 Antiquities Act, which allows presidents to protect sites considered historic or geographically or culturally important.

In a letter last month, Durbin and 15 other senators complained that Zinke's recommendations "threaten important natural, archaeological and cultural resources," especially Bears Ears, a 1.3-million acre site in southeastern Utah that is home to thousands of Native American artifacts, including ancient cliff dwellings and petroglyphs.

"National monuments have preserved our country's unique public lands, extraordinary history and our common culture as a people," the senators wrote in an Oct. 23 letter to Trump. "We urge you not to reduce their boundaries in any way."

Durbin and several other senators wrote a separate letter to Zinke seeking a meeting about the monument review, which they said has been conducted virtually in secret.

Zinke responded Thursday that he visited the four monuments that are being shrunk and met with or talked to lawmakers and governors in all four states.

"While the review does not affect the state of Illinois, I nonetheless understand your interest in this matter, and I appreciate the written comments you and your colleagues provided throughout this review process," Zinke wrote to Durbin.

Durbin has placed holds on the nominees in his leadership role. Spokesman Ben Marter said Durbin looked forward to meeting with Zinke, although no date has been set.

"That was probably harder than it needed to be, but the secretary has now reached out to schedule a meeting and Sen. Durbin is looking forward to it," Marter said.

Durbin has placed holds on four Interior nominees: Susan Combs, nominated as assistant secretary for policy, management and budget; Joseph Balash, assistant secretary for land and minerals management; Ryan Nelson, solicitor; and Brenda Burman, commissioner of the Bureau of Reclamation, which oversees dams and water projects in 17 Western states.

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