"It is your duty to hold federal agencies at bay, protecting the people in your state," said Ammon Bundy, according to the transcript of a telephone call he made on Saturday from jail and released by one of his lawyers.
Bundy also urged elected representatives in Idaho, Nevada, Oregon, Wyoming, Utah, Arizona, Washington state and Ohio to support the right to assemble.
Bundy and 10 others were arrested in Oregon in late January, most of them during a confrontation with the Federal Bureau of Investigation and state police on a roadside where a spokesman for the group, Robert "LaVoy" Finicum, was fatally shot. A 12th member of the group turned himself in to police in Arizona.
Two of those arrested have been released on condition that they wear electronic tracking devices while awaiting trial, leaving 10 of the former protesters, including Bundy, in custody.
Four armed anti-government protesters still at the Malheur National Wildlife Refuge were indicted last week with the 12 others on charges of conspiring to impede federal officers during an armed standoff at the compound.
The takeover at Malheur started on Jan. 2 when Bundy and followers seized buildings at the refuge in a protest against federal control over millions of acres public land in the West.
A judge cited the continuing standoff as an obstacle to the release of at least some of those still in custody. They are to be arraigned on Feb. 24.
Tensions have flared in the town of Burns, 30 miles (48 km) from the refuge, with hundreds of demonstrators and residents angry about the occupation and its supporters.
Bundy has released statements previously, defending the takeover and urging the four holdouts to stand down.
Members of the Burns Paiute Tribe, native Americans whose land previously encompassed the preserve, have criticized Bundy and his group.